Home network with one modem and two routers in series

Question: I have internet connection going from the modem to a tplink router. I have WiFi and internet connection. Now I would like to connect a Linksys router from a LAN output port of the first to the WAN port of the second, and create a second WiFi network, also connected to the internet. A friend of mine made it work in the past, but has suddenly stopped working (the lights went out or something). Could anyone please help me with the config's of both routers? Thank you
Comment: Did you research this at all? Just log into the 2nd Router, give it an IP address that is different than 1st Router but within the same subnet, setup WiFi, disable DHCP, then connect your feed from a LAN port on R1 to a LAN port on R2... Done. This process is well documented all over the internet, and here dozens of times, a few Google searches would find this answer in seconds.
Comment: @acejavelin. First of all thank you for the answer. Second, if you see my profile (specially on stackoverflow), you see that I'm not new to stackexchange and know the usual rules. I searched on the interwebs and tried several different setups. None of them worked. Thing is I don't understand half of what I'm doing. That's y I came up to superuser so someone expert in the subject could give me a "step by step", as great answers around here usually are.
Answer: Most home networks are best off with only a single box acting as a NAT gateway (router) and DHCP server. If your modem has those features and you can't turn it off there, then set up your wireless "routers" to act as simple APs rather than NAT gateways.
Many wireless routers don't let you turn off NAT, so you just have to turn off their DHCP server feature, and plug their LAN port into your home LAN, and leave their WAN port empty. That way they automatically bridge packets from LAN to WLAN transparently.


Bitcoin Core download crashed

Question: I was adding a new drive to my PC when Bitcoin Core download crashed ..no idea why, anyway I cannot reboot and have no access now, I was in the middle of slowly downloading the blockchain to get started on my node. Advice please, I do not want to start the slow process of downloading again if possible. Be gentle I am a complete newbie. Cheers Q
Comment: Welcome to bitcoin.stackexchange.com. Can you clarify exactly what you need help with? downloading software? initial blockchain download? reinstalling an operating system on a PC that won't start? Recovering data from a dead hard disk?
Answer: In the same folder as your wallet.dat file should be a debug.log file.
it is a log file that could reveal why your instance crashed.
If you post that file, or read it yourself (there is no sensitive info in log files AFAIK) then we can perhaps find the answer.

Bitcoin Core download crashed


How can I prevent IIS from trying to load a dll?

Question: My project is a Speech Server application using Windows Workflow. It runs as an app under IIS. It supports a plug-in system. Here is what is happening:

Load DLL into memory and set the type on an InvokeWorkflow control.
When the InvokeWorkflow control runs, it appears to correctly instantiate the workflow from the loaded assembly - it completes the Initialize method.
Everything crashes an burns, the target workflow is never executed.
I can resolve this by putting a copy of the DLL in the application's executing directory. The workflow then executes correctly

So it appears that IIS is trying to reload the assembly, even though its already in memory.
Is there anyway to alter or disable this behavior in IIS? Perhaps a hook I can write that will intercept the request to load the dll and use my own logic to do so?
Answer: Where are you loading the DLL from? You may be hitting some runtime security constraints with the DLL or its location.


Array index out of bounds. Interface Packets dropped: String (PowerShell)

Question: Wrote a script to create incidents (objects) in bulk in SCSM (Microsoft System Center Service Manager) using PowerShell. The script pulls the data required from a CSV file. I am running into the following error:
<code>New-SCSMIncident : Index was outside the bounds of the array.
At C:\Users\portalservice\Desktop\scripts\Incidents\BULK_Create_Incidents.ps1:83 char:5 +     New-SCSMIncident -Title $Title -Description $Description -AffectedUser $Affe ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo          : InvalidOperation: (Interface Packets Dropped :String) [New-SCSMIncident], IndexOutOfRangeException
+ FullyQualifiedErrorId : NewIncident,SMLets.SCSMIncidentNew
</code>
When I echo the contents of the array I see normal data... it all looks correct. Here is my script:
<code># Script designed to create tickets in bulk, reading the information needed from a CSVfile
# Tailored for incidents, can be modified to work with any work item
# SirLearnAlot 2015

# NOTES: Modify the $path variable to match the path of the data file being imported

# Import the smlets module
ipmo SMLets
Write-Host ""
Write-Host "Importing Smlets..."

# ---------------------------------------- Variable Decleration ----------------------------------------
Write-Host "Getting the classes needed..."
# Get the incident class
$IncidentClass = Get-SCSMClass -Name System.WorkItem.Incident$
# Get the CI Class
$CIClass = Get-SCSMClass -Name COMPANY.CI.Class$
# Get the Relationship we want to add (Affected Items)
$RelWIaboutCI = Get-SCSMRelationshipClass -Name System.WorkItemAboutConfigItem$
# Clear the error variable incase it contains anything already
$error.clear()

# --------------------------------------------- Data Import --------------------------------------------
# Import the CSV Data file containing list of incidents to create and their information
Write-Host "Importing CSV Data File..."
$path = "C:\Users\portalservice\Desktop\Script Data\Work Item Creation\Incidents\11.12.15\data.csv"
$data = ipcsv $path
if ($error -like "Could not find file *")
{
    Write-Host "Encountered an error while importing the data file from '$path'. Please verify the path directories and file exist and run the script again."
    exit
}
else
{
    Write-Host "Successfully imported data file!"
    Write-Host "Beginning ticket creation..."
    #pause
}
# ---------------------------------------------- Execution ---------------------------------------------
# Begin going through file line by line
foreach ($case in $data)
{
    # Clear the error variable
    $error.clear()

# Visual Formatting
Write-Host ""
Write-Host "----------------------------------------------------------------------------------------"
Write-Host ""

# GETTING THE INFORMATION FROM DATA FILE AND STORING IN VARIABLES
# Get the Info for the Incident to create
$Title = $case.Title
Write-Host "Got case title: $Title"
$Description = $case.Description
Write-Host "Got case description: $Description"
$AffectedUser = $case.AffectedUser
Write-Host "Got case affected user: $AffectedUser"
$Classification = $case.Classification
Write-Host "Got case classification: $Classification"
$Impact = $case.Impact
Write-Host "Got case impact: $Impact"
$Urgency = $case.Urgency
Write-Host "Got case urgency: $Urgency"
$SupportGroup = $case.SupportGroup
Write-Host "Got case support group: $SupportGroup"
$PrimaryOwner = $case.PrimaryOwner
Write-Host "Got case owner: $PrimaryOwner"
$Vendor = $case.Vendor
Write-Host "Got case vendor: $Vendor"
$Customer = $case.Customer
Write-Host "Got case customer: $Customer"
$ReportedOn = $case.ReportedOn
Write-Host "Got date reported on: $ReportedOn"
# Get the name of the correct CI to add
$CIToAddNum = $case.CI
Write-Host "Got case CI: $CIToAddNum"
# Apply the non-OOB Values to the property hash table
$PropertyHashTable = @{"Vendor" = $Vendor; "Customer" = $Customer; "Reported_On" = $ReportedOn}

# INCIDENT CREATION
Write-Host "Attemping to create Incident from case data..."
New-SCSMIncident -Title $Title -Description $Description -AffectedUser $AffectedUser -Classification $Classification -Impact $Impact -Urgency $Urgency -SupportGroup $SupportGroup -Bulk
# Checks to see if the there is an error, if so displays a warning message and exits
if (!$error)
{
    Write-Host "Incident creation successful."
}
else
{
    Write-Host "$error"
    Write-Host "Error creating the incident. Check the incident creation code and run this script again."
    exit
}

# INCIDENT RETRIEVAL (POST-CREATION)
Write-Host "Attempting to retrieve incident for modification (Adding Customer, Vendor, and Reported On date to ticket)"
$Incident = Get-SCSMObject -Class $IncidentClass -Filter "Description -like '%$Description%'"
# Checks to see if the retrieval failed, if so displays error message and exits script
if ($Incident = $null)
{
    Write-Host "Incident retrieval failed. Check the incident retrieval code and run the script again."
    exit
}
# Apply the property hash table to the retrieved incident
$Incident | Set-SCSMObject -PropertyHashtable $PropertyHashTable

# ADDING THE CI TO THE INCIDENT
# Get the CI from the CMDB
$CIToAdd = Get-SCSMObject -Class $CIClass -Filter "DisplayName -eq '$CIToAddNum'"
if ($CIToAdd = $null)
{
    Write-Host "Cannot find $CIToAddNum in the database, this CI does not seem to exist or the code to retrieve the CI failed. Please import the CI into the SMDB or fix the retrieval code and run this script again"
    exit
}
# Attempt to add the CI to the Incident (Create a new relationship)
# Note: Due to a bug the -bulk paramater is required
Write-Host "Attempting to add $CIToAddNum to Incident..."
New-SCSMRelationshipObject -Relationship $RelWIaboutCI -Source $Incident -Target $CIToAdd -bulk
# Check if script throws error (cannot find the CI from the data file in our SMDB)
# If so provides error message and exits, otherwise provides success message
    if ($error -like "Cannot bind argument to parameter 'Target' because it is null.")
    {
        Write-Host "Encountered an error while trying to add $CIToAddNum to $IncidentNum, this CI is not in the Service Manager Database or there was a problem retrieving it. Please import the CI into the SMDB or check the retrieval code and run this script again"
        exit
    }
    else
    {
        Write-Host "Successfully Added!"
    }
}
Write-Host ""
Write-Host "Success! All Incidents Corrected :)"
</code>
Not sure what the problem is here, any ideas?
Answer: Hit this same problem, my solution was to instead use New-SCSMObject.
Here is a simple example:
<code>    $irprops = @{Title = 'test'
                 Description = 'test descripton'
                 Impact = (get-scsmenumeration -name 'System.WorkItem.TroubleTicket.ImpactEnum.Low')
                 Urgency = (get-scsmenumeration -name 'System.WorkItem.TroubleTicket.UrgencyEnum.Medium')
                 ID = "IR{0}"
                 Status = (get-scsmenumeration -name 'System.WorkItem.TroubleTicket.ImpactEnum.Low')
                 Priority = 2
     }

     $ir=new-scsmobject -Class (get-scsmclass -name 'System.WorkItem.Incident$') -PropertyHashtable $irprops -PassThru
</code>


When customizing your iWatch face the time changes to 10:09

Question: I'm curious why Apple uses the 10:09 time as a default when changing your Apple Watch face. I've seen this even in their marketing content. Is it the best time to be displayed for marketing purposes? Because it's somewhat symmetrical? The date stays consistent to the day.
Answer: This is a solid style convention about clocks in advertising
It serves to both:

Show company logo (usually on the top of the watchface) clearly and
Create a psychological feeling that the clock is "smiling" (\ /) rather than sad (/ \) or on another meaningless position.

There's also this very good article on The New York times covering the issue

It can also have a golden rectangle-related effect
MONZINGO further says that the aproximation with the Golden Rectangle also helps the visual appeal (altough he also says that the 8:18, or "sad face", is also close to the golden ratio).
Comment: Other interesting article: http://mentalfloss.com/article/22461/why-1010-default-setting-clocks-and-watches
Comment: 14:50 is also used for the same reasons
Comment: @AndrewMartin, interesting, but something made me feel unease about this arm position
Answer: Through history, the advertising convention for time in clocks was 10:10. Nobody disputed that, in any case some watch makers used different positions for the seconds: Rolex has a preference for 10:10:31; TAG Heuer sets its wristwatches to 10:10:37; Bell & Ross displays time at 10:10:10. Timex is one example of someone deviating from the norm: they set the time at 10:09:36.
As for Apple, there's not an official release, more like speculations:

By setting the Apple Watch to 10:09, Apple is able to pay homage to
  the long lineage of mechanical watches that preceded it. It's also
  Apple's way of declaring that the Apple Watch is, despite all of its
  advanced digital components, a bonafide timepiece that deserves to be
  mentioned in the same breath as more traditional watches. From Apple's
  vantage point, the Apple Watch isn't a smartwatch. On the contrary,
  it's a modern watch that just happens to be extremely smart. The
  difference is subtle, yet distinctly important.
Apple has never once referred to the Apple Watch as a smartwatch. For
  a company as detail oriented as Apple, this is no coincidence. Apple
  is effectively saying that the Apple Watch doesn't belong in the same
  category as the Galaxy Gear (itself set to 12:45) or the lazily named
  Sony Smartwatch 2. The Apple Watch, Apple is telling us, is an
  elegantly designed device that is as much about fashion as it is about
  advanced technology. The Apple Watch, Apple is telling us, is a modern
  take on a traditional watch, not a geeky smartwatch meant for a niche
  audience. Setting the time on the Apple Watch to 10:09 is arguably a
  reflection of this mindset and underscores Apple's own understanding
  of what the Apple Watch is and who the intended audience is --
  everyone.
  From: Why is time on Apple Watch promotional ads set to 10:09?

Apple has a history of choosing a display time that has some
  significance, famously setting the time on all of its iPhone
  promotional materials and images to 9:41, the approximate time of day
  when Steve Jobs first unveiled the iPhone to the world back in 2007.
So why 10:09 for the Apple Watch? Apple appears to be making a
  statement about being ahead of the curve when it comes to
  smartwatches, and the facts back this theory up.
  From: Here's why the Apple Watch always shows the time as 10:09 in advertisements

I think this is more about symmetry, about attention to detail, than
  about being ahead of the curve. At 10:10, the hour hand will be 1/6 of
  the way between the 10 and the 11 on the watch face. If the minute
  hand is precisely on the 2 (as it would be at 10:10), the minute and
  hour hands would not be symmetrical. At 10:09, the hands would be much
  closer to symmetrical perfection.
  From: Why Apple Watch shows 10:09 in all its ads

However...
As you may see, it's all speculation, the only real fact is the classic 10:10 time, where 10:09 is really close, so one could also speculate this has some marketing reasons, but it could also be (and as a matter of fact, probably is) a slight difference that tested better than 10:10


Difference between "generate" and "create"

Question: What is the difference between these two sentences:

The new development will generate 1,500 new jobs
The new development will create 1,500 new jobs
Comment: They seem about the same to me.
Comment: Yes, they have the same meaning.
Answer: The difference is really a question of immediacy.
If I build a factory that offers employment to 1,500 workers, I create those jobs.
But if, as in the motor industry, I build a factory that offers employment to fewer workers, but leads to subsidiary industries that supply the factory with parts and to shops and restaurants that serve the workers' needs, the factory's activities generate the additional jobs.
That's to say that the building of the factory leads indirectly, rather than directly, to the additional jobs. The other industries and services are dependent for their existence on the factory.
Answer: Normally "generate" emphasizes a mechanical process, and "create" emphasizes, well, creativity. That distinction doesn't really come into play in the example you posted, so there is little difference between your 2 sentences.

Difference between “generate” and “create”


How could you disclose what you like and have someone respond with what you want without revealing who you are?

Question: Bob likes Apples and Oranges (virtual, not physical). Alice and Eve are fruit sellers (again, virtual, not physical). Bob wants to indicate his appetite to buy one Apple and one Orange without revealing who he is. Alice and Eve want to sell to Bob but they can't know Bob's identity. How does Bob communicate his preference to buy, and then take receipt, without Alice and Eve ever knowing who he is and without using a central authority?
Comment: "Bob shares what he likes with Alice" needs a definition. It's not even clear if that's information (as in _Bob communicates to Alice the information that he likes 42_) or something physical (as in _Bob likes cake and shares a cake with Alice_). Assuming the former, it's not clear how Bob knows about Alice in the first place; If he cares that Eve knows he likes 42; what kind of communication can occur between Bob and Alice; if Eve is able to replace 42 with 43.. For this and many other reasons that do not fit, the question is not precise enough. It must be improved, or will get closed.
Comment: Are you referring to the [Soviet Spy Game](https://www.scottaaronson.com/blog/?p=2091#comment-329963), or something adjacent to it? Perhaps like a zero-knowledge proof-of-not-cheating for [Go Fish](https://en.wikipedia.org/wiki/Go_Fish)?
Comment: Sorry, I have edited the question. Is it now more clear?
Comment: First and foremost, thank you very much JamesTheAwesomeDude for your answer. Can you possibly suggest additional reading material, or topic titles? I am keen to learn more. I don't really know how to search for answers to my problem. Does it fit within a particular sub-field of cryptography?
Comment: https://en.wikipedia.org/wiki/Alice_and_Bob
Comment: Is the problem Bob's anonymity, or Alice's identity? My answer covers the first question (as stated in the title), but [What does it even *mean* to be "Alice, the fruit seller"?] is a perennial and eternal question at the scope of the internet elders and other zany projects
Comment: A stupid solution, get Derek (D), a trusted fourth party. D will know identity of all 3, but will not reveal.
Answer: All Bob needs is to generate an Ephemeral key: just make (say) an RSA key, use it to initiate and proceed with communications with Alice, then delete it when he's done, taking care never to use it to process any personally-identifying information.
In fact, this is what web browsers do every time you connect to a website: by default, only the server has a certificate anchoring its identity; clients are anonymous until or unless they supply authentication. Your queries to, say, Searx are confidential, known only by the host and the anonymous client which started that TLS session.
(The bit about "no central authority certifying Alice" is a massive, separate question -- it is the puzzle which X.509, DANE, and an entire host of decentralized proto-solutions are still struggling to solve to this day; but I'll include a proto-solution to it as well.)
With any public-key cryptosystem, it's trivial to implement an ephemeral or "anonymous" key, by simply not attaching identity attestations to a freshly-generated public key and then throwing it away afterwards; if you're only concerned with the authenticity of one party (Alice is a recognized fruit seller or someone whom Bob otherwise knows the public key of; Bob is an anonymous client with no identity persisting beyond the scope of a single discussion session), it's quite easy -- For example (all messages listed are both signed by the sending key and encrypted by the receiving key):
<code>Bob: (Acquires Alice's putative pk_A)
Bob: (Generates a keypair sk_B, pk_B)
Bob -> Alice (sk_B -> pk_A): "Buying oranges for 3 bitcoin, reply-to [pk_B]"
Alice -> Bob (sk_A -> pk_B): [initiate zero-knowledge proof of orange possession]
Bob -> Alice (sk_B -> pk_A): [challenge proof]
Alice -> Bob (sk_A -> pk_B): [complete proof]
Alice -> Bob (sk_A -> pk_B): "send 3 bitcoins to [btc_A] if you want them"
Bob -> Alice (sk_B -> pk_A): [transaction]
Alice -> Bob (sk_A -> pk_B): [oranges]
Bob: (deletes sk_B and all trace of pk_B off his computer)
</code>
In the real-world, something like this happens if you buy something from an online merchant using a burner e-mail (or no e-mail) and either General Delivery or inherently digital data served over the same TLS connection, though without a "proof" of the online merchant's legitimacy (which, again, is a whole separate scope from merely allowing bidirectional secure communications with an anonymous participant).

[Note that Bob and Alice are switched from their canonical roles in your question; I have written my answer to reflect that, but, in the future, you should use "Alice" to represent the initiator/sender of communications and Bob as the recipient or secondary participant. Additionally, "Eve" is used to denote the malicious party -- the hacker or "Eavesdropper" -- who may be just eavesdropping, or may be launching interactive or invasive MitM attacks; her abilities are generally assumed to comprise control of the network.]
Comment: That is very clear, thank you. And I will be sure to use the correct nomenclature going forward.
Comment: @user13017275 Re your request for further reading: [overview from Linuxjournal](https://www.linuxjournal.com/content/understanding-public-key-infrastructure-and-x509-certificates); [limitations from Neil Rickert](https://nwrickert.wordpress.com/2011/03/23/pki-is-broken/); [Christian Mock at CCC 2003](https://www.tahina.priv.at/talks/pki-sucks.pdf); [2 conference talks and a research project from EFF](https://www.eff.org/observatory); [Real-world attack leaked by Christopher Soghoian](https://archive.is/KgOni#selection-2513.25-2513.243)
Comment: Thanks very much.
Comment: See also [answer to "Why NaCL does not provide anonymous public key cryptography?"](https://crypto.stackexchange.com/a/47992/8287) for earlier examples of this same line of thought


Implementation of Google Job Posting

Question: I have read through this article: https://developers.google.com/search/docs/data-types/job-posting#JobPosting-definition and found where the Required Properties are that I will need to add to a job posting. I'm not sure how to actually do this. I saw mention of it being done with JSON but I am unfamiliar with it. Is there a simple way I can use html to add these properties to a job post, such as one that would appear in a blog post of a Wordpress site?
Answer:
Is there a simple way I can use html to add these properties to a job post, such as one that would appear in a blog post of a Wordpress site?

No.
HTML is a document format, it isn't well suited for providing data with the level of structure demanded by this type of problem.

I saw mention of it being done with JSON but I am unfamiliar with it.

That's the format that the API you want to use expects data to be provided in (it is also the format that the vast majority of web services use). You need to get familiar with it.
Read the website and the specification, and find a JSON encoding library for whatever programming language you are using to connect to the Job Posting API (e.g. the JSON object for JavaScript).
Answer: Thank you for your response Quentin. Unfortunately the client needed something ASAP so I didn't have the time to learn JSON. I did however find a WP plugin that did the trick. It sis called WP Job Management: https://wordpress.org/plugins/wp-job-manager/.
Answer: Here I implemented for one of my client.
They were running jobs portal website. so i have done job posting schema using json_ld. here is the code i have used inside my page
<code><script type="application/ld+json">
{
  "@context": "http://schema.org",
  "@type": "JobPosting",
  "baseSalary": "100000",
  "jobBenefits": "Medical, Life, Dental",
  "datePosted": "2011-10-31",
  "description": "Description: ABC Company Inc. seeks a full-time mid-level software engineer to develop in-house tools.",
  "educationRequirements": "Bachelor's Degree in Computer Science, Information Systems or related fields of study.",
  "employmentType": "Full-time",
  "experienceRequirements": "Minumum 3 years experience as a software engineer",
  "incentiveCompensation": "Performance-based annual bonus plan, project-completion bonuses",
  "industry": "Computer Software",
  "jobLocation": {
    "@type": "Place",
    "address": {
      "@type": "PostalAddress",
      "addressLocality": "Kirkland",
      "addressRegion": "WA"
    }
  },
  "occupationalCategory": "15-1132.00 Software Developers, Application",
  "qualifications": "Ability to work in a team environment with members of varying skill levels. Highly motivated. Learns quickly.",
  "responsibilities": "Design and write specifications for tools for in-house customers Build tools according to specifications",
  "salaryCurrency": "USD",
  "skills": "Web application development using Java/J2EE Web application development using Python or familiarity with dynamic programming languages",
  "specialCommitments": "VeteranCommit",
  "title": "Software Engineer",
  "workHours": "40 hours per week"
}
</script>
</code>
Here is the one of site that implemented good Scheme Refer : https://allgovernmentjobs.in/ . there you can find the job posting schema.
you can check this url : https://allgovernmentjobs.in/latest-government-jobs into the google structural Data testing Tool : https://search.google.com/structured-data/testing-tool/u/0/ and fetch the url. You will get the idea about how the code as implemented and it helps for the better results in google search

Implementation of Google Job Posting


Why is the interval between C# and F a diminished 4th?

Question: Wouldn't it be the major third as well?
Comment: It's all about the note names! C# to E# would be a major third. C# to F is a diminished 4th even though it sounds the same
Answer: The number of an interval is always determined by how many letter names (or staff positions if you think about written music) they encompass. C to F encompasses four letter names (C, D, E, and F) - therefore it has to be a fourth of some kind (note, it doesn't matter if one or both of the notes has a sharp or flat). After that we have to count semitones to determine the quality of an interval (i.e. if it's Perfect, Diminished etc.). For the number of semitones needed for each interval, you can look at this chart (ignore the bit about tuning systems)
You are of course right that the diminished fourth sounds the same as a major third. They are, as we say, enharmonic, but for theoretical reasons we distinguish between the two. This is similar to how we do with notes as well. C# and Db, sound the same but they get different names based on the context they appear in. Incidentally, the distance from a Db to F would actually be called a major third, since D to F encompasses three letter names (D, E and F).
Comment: @ppadru1 Again, it comes down to counting letter names - if you want a third above C (weather it be C#, Cb or C natural) - you will need an E of some sort because C to E makes three letter names (C, D and E). To make a major third specifically we need 4 semitones (see added link above) so we start from C# and go up four semitones which lands us on the note E#. We can't call it F, because then we'd have a fourth of some kind, so it needs to be an E, and since it is a semitone higher than E natural, we just call it E#.
Comment: @ppadru1 I'm not sure I understand your question? Do you mean what if we called the starting note Db? It's the same procedure. If you want to find a major third above Db, you count up three letter names, i.e. D - E - F . Which means your second note needs to be an F of some kind. Then you count four semitones and you land on an F natural. So that would be your major third. So there are always two parts to finding/naming an interval: the *number* of the interval, determined by how many letter names. and the *quality* of the interval determined by distance in semitones.
Comment: This is helpful.  Steps from the tonic doesn't matter, but the number of notes do.  Why, in this instance, do we call the major third E#, rather than F?
Comment: What if I were to call the scale a Db?  How does that change the nomenclature?
Answer: If you spell it Db - F (or C# - E#) it's a major 3rd.  Spell it C# - F then it's a diminished 4th.
Same sound.  Very likely a different harmonic function.  We hope the composer chose the spelling that best clarifies the harmony, not the one that looked 'easier'.
If you have no problem with being scene at the seen of an accident, or sending your mail a Valentine in the male, I'll allow you to spell a major triad as B#, Fb, G.   Otherwise, don't!
Comment: ...and B-double-sharp-to-F is a triply-diminished fifth.  Horrors!


How to make a good PDF résumé without purchasing Adobe Acrobat?

Question: How to make a good PDF résumé without purchasing Adobe Acrobat (or anything else)?
Comment: Use the trial version of Adobe Acrobat.
Answer: I use Word for formatting and CutePDF Writer to print it to PDF.
Comment: newer versions of Microsoft Words allow "save-as PDF" natively, now.
Comment: Been using CutePDF for years. It's free, it works, and you can send ANYTHING you can print to a PDF with this tool.
Comment: PrimoPDF or CutePDF all the way.
Answer: Try LaTeX -- it would also look better then.
Start with http://en.wikipedia.org/wiki/LaTeX and http://miktex.org/
Comment: If you'll find LaTeX a bit though, search for LyX (same syntax, but more easy at first sight).
Comment: Having done both, I disagree. Everybody and their brother has opened a WYSIWYG editor at some point. And there must be hundreds of templates out there in the world.
Comment: @dag And LyX has a couple of pre-made example files for a CV, which look pretty good when the PDF is generated.
Comment: Having dabbled in Latex, I can't recommend this. If he said "hey I need to make a document with lots of maths" then yes. For a resume  learning Latex is far too much work.
Comment: @jcollum Learning how to make a reasonably non-ugly document in WYSIWYG editor in a finite time is much harder than learning basic LaTeX.
Comment: This is kind of a non-answer. Writing a good looking resume in LaTeX is much harder than doing it in WYSIWYG editor, if you are a non-programmer, which I assume OP is (given he uses Adobe Acrobat). Answers like this is akin to "Hardware XY doesn't work well on windows XP. What to do?" - "Install linux."
Answer: I use OpenOffice.org's word processor to create the resume and then export it as a PDF - it works quite well. If you are used to Microsoft Word, it should be fairly easy to adopt OpenOffice.org - it's very similar to old versions of Word (before the Ribbon). A few things are in different places, but it's not that bad to get used to.
Since you are using Windows, if you have Microsoft Word installed, that should also have a way to export to PDF (or you can obtain a PDF printer, which allows you to create PDFs in the same manner that you would print a document to a regular printer).
Another option would be to learn and use LaTeX. However, I wouldn't recommend this if you just want to write and maintain your resume. It's far more useful for things like scientific and engineering publication writing (although OO.org and Word are getting better at that).
Comment: I just proposed it as an option. Would I recommend it? Not for most people. OpenOffice.org or Microsoft Office and some form of PDF export tool (if it's necessary, depending on the version you are using) would be a far easier choice. However, all options should be presented so the OP can choose what he feels is best.
Comment: Why learn LaTeX - or any other project, for that matter - when you can use free tools, or the built-in functionality in Office 2007?
Answer: MS Word 2007 has a built-in PDF exporter
Comment: Exactly what I was going to say. For Office 2007, you need to download the PDF export package separately. Word 2010 (as of the beta) has it built in.

http://www.microsoft.com/downloads/details.aspx?FamilyID=4d951911-3e7e-4ae6-b059-a2e79ed87041&displaylang=en
Answer: LaTeX is a great choice for resumes and cover letters, or anything that you want to look neat and professional.
If you use a premade template (like the ones here), then it becomes very simple. No need to learn a ton of complicated new syntax - all the pieces you are likely to use already exist in the examples, just replace their text with yours and you are ready to go. Of course, learning LaTeX can be very helpful in other areas as well. Some folks who recognize documents created with LaTeX may also take you more seriously if the position is computer- or math-related.
If you don't feel like using LaTeX, lots of pdf printers exist. There is CutePDF, as mentioned by steve, but the one that I usually use is Bullzip.
Answer: For extra geek cred, write your resume in XML, format it with XSL-FO and output a PDF. ;-)
Comment: or asciidoc -> docbook -> xsl-fo -> pdf :)
Answer: Scribus has always served me well for this purpose and many others.
Answer: There is PDF Creator. It installs as a printer, and can quickly generate a PDF from most any program you can print from.
Answer: Office 2007 and Office 2010 allows you to save as PDF without the need of things like PDF printer drives with the added benefit that it makes for "search/copy/paste-able" PDF's with even the option to generate table of contents.
I believe for 2007 you have to download the Addin but 2010 has it by default:
http://www.microsoft.com/downloads/details.aspx?FamilyId=4D951911-3E7E-4AE6-B059-A2E79ED87041&displaylang=en
http://office.microsoft.com/en-us/word-help/save-a-file-in-pdf-format-HA010064992.aspx
Answer: I would also recommend OpenOffice since it's free and supports multiple file types.  You could also visit http://en.pdf24.org/ and have them convert it for you.  Or you could download and install their program which makes pdf24 appear as a printer on your machine.  This allows you to "print" out a pdf version of your resume which you can then save.
Answer: Its called pdfCV it will help you create your Resume(CV) online as a PDF in minutes, where ever you are or on whichever computer you are using.
http://pdfcv.com/
Answer: Install a PDF printer, like:
doPDF,
PrimoPDF,
BullZip PDF
Use your favorite word processor, like Microsoft Word, and then select your PDF Printer that you just installed.  It would print and ask you to name the resulting PDF file.
Personally, for simple PDF creations, I use doPDF.
If I need to embed the font that I am using in my document, I prefer to use BullZip PDF.


Join two pipes with independent rotation?

Question: I'm planning to build a table tennis robot using an Arduino controller for the location/placement logistics and control, but I'm stuck on one physical detail and don't know where else to ask. I want to be able to rotate the end of the pipe independently of the base, but I can't find any fixtures that would allow for this. To clarify what I'm looking for, think of joining two pipes together axially - typically the joint will be fixed and they won't be able to rotate in the coupling. I'm looking for a coupling that will allow one end to rotate independently of the other end with minimal friction so a small servo can perform the rotation (obviously being water tight is not a requirement :-) ). Anybody know what the terminology for such a coupling is, or an exact example of one? I'm looking for an opening that can fit a ping pong ball, so 2" inner diameter should be plenty. Thanks for any insight!
Comment: we once covered robotics here, but it's now considered off-topic
Comment: did you complete the robot ? i am also thinking of making one and would like to save time, if you have already made significant progress
Comment: It's certainly interesting, but is it electronics or EE related?
Comment: @r-v, I'm not done but I've made significant progress; it does work though :-) I ended up purchasing a 3D printer and then making my own outer bearing race.. kinda hard to describe, but similar in principle to how a BMX gyro/detangler.
Comment: A picture or sketch would be enormously helpful!
Answer: When you say joining two pipes, do you mean at right angles, or axially?
You could use a ball bearing, with the outer race of the bearing press-fit inside one pipe, and the second pipe press fit inside the inner race.   A large linear bearing would work too (but cost a lot).
Do you have access to a lathe?   A slip fit between two pieces of delrin or metal and delrin might work---all the gearing and linear bearings in some modern printers and scanners work much like this.
Comment: Axially (I updated the question to reflect that). I thought about something like a large ball bearing but I was having trouble finding the right sizes and cost was getting up there for those as well. I don't have direct access to a lathe, but I might be able to work something out (my wife went to the local engineering college)... still open for other ideas but I'll look into that a bit.
Answer: Sintered bronze bearings (often oil impregnated) can be a useful technology, they are both thinner and cheaper than ball bearings.
Sometimes a piece of metal or plastic pipe can work as a sleeve bearing.
Depending on load and life cycle, a variety of plastics or even hardwood can be used for do it yourself bearings.
For an old-school approach, if you have a polished shaft, pouring a babbit metal around it may be an option.   A newer take on that idea is epoxy-teflon composites, such as Moglice.
If you are playing around with mechanics, you should have have catalogs from the likes of small parts, msc industrial, mcmaster (probably online only), northern hydraulics, and some of the radio control model outlets kicking around for light reading - it's useful to learn about the range of items that must be manufactured to enable an industrial society, and what sub-varieties thereof are affordable from various sources.  And make a point to browse your discount auto-part store and the dusty corners of anything still resembling a true hardware store in your area.
Comment: Over the weekend I came up with an idea of using two bolts on the outside of the pipes going along the entire length. On the back end of the pipe (doesn't rotate), it would go through two holes. On the front end, it would go through slotted holes, allowing the pipe to rotate on the rods. This morning I got to thinking about your suggestion of Moglice and then Delrin. Now I'm thinking of using two PVC tubes coupled together. Do you know if any of these compounds bond to PVC? (don't want them to). Is it possible to melt down Delrin and pour it into a gap? (Such that it creates a bushing?)
Comment: After doing more research I realized that PVC can have a lower melting point than Acetal/Delrin. I ended up purchasing a sintered bronze bushing from McMaster Carr - hopefully it will work well :-) Thanks for the input.
Comment: Probably you don't want to run a bushing on the threads of a bolt, but if there isn't much mechanical load you will get away with it.
Comment: I just did a rough assembly last night and it seems to be working. The setup is 2" PVC->2" PVC coupling->Bushing->1.5" PVC. There is a little bit of slop, but not enough to concern me - I might see what other techniques I can utilize to reduce the slop later on in the project.


Someone I know via Facebook and who lives in Pakistan wants me to send him money - should I?

Question: A Facebook friend of mine named "Eve Amar Saab" has asked me to send him money via Moneygram to him. He lives in Pakistan.  However, he gives me a different name-"Shaban Masih Karamat Masih."  Is this a scam or at least a red flag?
Comment: I wouldn't necessarily say that this is a scam, any more than say the typical GoFundMe appeal is a scam.  He wants the OP to send him money.  If there's no trickery (e.g. I send you $5000 in fake money and you send back $4500 in real money), then it's not a scam, it's just giving money.
Comment: It's a scam.  DO NOT reply in any way AT ALL.  Note that if you do, it is possible YOU YOURSELF could be in VERY serious trouble for being involved in money laundering and other crime.  YOU are who the authorities will go after.  DO NOT reply in any way AT ALL.
Comment: Let's suppose someone you met in the pub and struck up a friendship with asked you to give him some money. Would you? Would you still give him money if he said he could only take the money in a specific form, and asked you to actually give it to someone with a different name?
Comment: (In other words - yes, this is a scam. Even if you can't work out in what way you're being scammed.)
Comment: Facebook was recently compromised, he may have lost control of his account,
Answer: Most likely this is a scam. I had an Arab friend that I knew by one name when we worked together, but he goes by a different last name today. Maybe this flexibility with last names is something in Islamic cultures we don't see in the US. If someone knows either way, please set me straight.
Supposing we ignore the red flag of the name discrepancy and further suppose it to be innocent cultural variation. How would you ascertain this is not a scam? Have you communicated with him via a different (non-internet) channel? Whenever I feel a prickling in my thumbs about something, I look up a phone number or a snail mail address. In fact, just this week, suspecting a fraud had been perpetrated in my name, I drafted a stiffly-worded letter to the State of Michigan and sent it off registered mail.
Scammers are unlikely to spoof non-electronic communications channels when you choose the channel and the address. Frankly, I think you're being scammed.
Answer: So there are soooooo many places THIS question could go...!
THE ONE TRUTH IS THAT WHENEVER SOMEONE HAS TO ASK, "IS THIS A SCAM?", THE ANSWER ALMOST ALWAYS SHOULD BE OBVIOUS -- YES!!!
If you're unsure of the situation (and you know FAR MORE than we ever can) then your first reaction should be to follow your instinct and not do it.
The fact the person is now giving you a DIFFERENT name to send the money to should be an automatic red flag!
Apart from the fact you will likely never see your money again, you don't really KNOW who this person is, and you could find yourself on watchlists and involved in the kinds of things that nightmares are made of.
Having covered the obvious (and assuming you might still be willing to entertain this harebrained idea), is this someone you only know via Facebook?  Under what circumstances did you meet, and why are they asking you for money now?
How much do they want, and do they intend to pay you back?  Even if they did agree to pay you, how could you ever collect?
You need to be VERY, VERY CAREFUL!  You don't know what is happening on the other end and where this might lead, unless this is a person you know far better than some social media account.
Comment: He now tells me that it is his brother's account and he says he does not have any account because he cannot "afford money."
Comment: If you're sending money via MoneyGram, it doesn't REQUIRE any kind of account.  And if he can't "afford money", what does he live on?  How does he manage to have a computer to contact you with?  Even if he's using a cyber cafe, they don't give you free access, so how does he pay for that?  It all leads back to the questions I gave in my answer about how well you know him.
Comment: Thank you!  I am asking him these questions now and awaiting his response.
Comment: DO NOT reply in any way AT ALL. Note that if you do, it is possible YOU YOURSELF could be in VERY serious trouble for being involved in money laundering and other crime. YOU are who the authorities will go after. DO NOT reply in any way AT ALL.
Answer: DO NOT SEND MONEY
If you are lucky, this just a scam and you'll just loose your money. But it's also possible that this related to some money laundering scheme or you are being used as a money mule. Could be just criminals but it could also be related to a terrorist organization in which case you would commit a serious crime and potentially end up in jail.
DO NOT SEND MONEY


What fuel should I use for my flamethrower turrets?

Question: Version 0.13 adds flamethrower turrets to the game. They can be operated with crude oil, heavy oil or light oil. Does the choice of oil have any impact on their performance? Also, which one is the more economical choice regarding crude oil consumption (heavy and light oil are made from crude oil and light oil can be made from heavy oil)?
Answer: Does the choice of oil have any impact on turret performance?
Yes. Heavy Oil gives 5% damage bonus, and Light Oil gives 10% bonus.

Which one is the more economical choice regarding crude oil consumption?
As Oil Processing produces large amounts of Petroleum (at least 40% of output), which is not useable in flamethrower turrets, and rate of fuel consumption does not change with fuel type, crude oil will be most economical choice.
What fuel should I use?
If you are interested in most economic choice, Crude Oil is the fuel of choice. If you want most DPS from your turret setup, use Light Oil. In most practical setups, there would be noneven ratio of production/consumption of different oil products, so you are probably want to use what you have in excess.
Comment: @Philipp Liquid wagons were invented after my comment, too, making the different oil products equally practical to transport.
Comment: @JSQuareD yes, but there I compared "how much crude oil should you pump to deal X damage". Different metrics will give different results.
Comment: Crude Oil is also more practical because: a) it can be directly piped from an oil well if defending an oil outpost with no processing required; b) it can be transported easily as an item (oil barrel) using either robots or trains from a centralized oil station.
Comment: The second part of the comment by @Darkhogg is a bit outdated: Since version 0.15, every liquid (except steam) can be transported via barrels.
Comment: If you compare crude / heavy / light in terms of how much petroleum they can be converted into, crude is actually the most valuable. This makes it the least economical choice for your flamethrower turrets.
Comment: @Revolver_Ocelot assuming your crude production is primarily determined by petroleum consumption (which it is for most factories) then using the least petroleum equivalent will lead to pumping the least crude oil per damage.
Answer: What is the most cost effective fuel?
When trying to find the most economical fuel it is best to calculate how much it costs to convert one of the fuels to another.
The basic recipes as of v1.1.36:
Advanced Oil Processing:
100 CO -> 25 HO + 45 LO (+ ...)

Heavy Oil Cracking to Light Oil:
40 HO -> 30 LO

When using 3 * Tier 3 Productivity Modules the productivity rises to 130%, which means that we should multiply the outputs with 1.3.
So when put into one equation:
100 CO -> (25 * 0.75 * 1.3 + 45) * 1.3 LO
100 CO -> 90.1875 LO

That means that crude oil is the most economical fuel of them all.
If you want the most DPS though, you should use light oil to get an extra 10% damage boost.
Comment: You failed to include the petroleum produced by advanced oil processing. If you compare crude / heavy / light in terms of how much petroleum they can be converted into, crude is actually the most valuable. This makes it the least economical choice for your flamethrower turrets.
Answer: The other answers regarding which oil is the most economical choice are incomplete. Typically, most of your oil is ultimately consumed as petroleum. So it is natural to compare the oil types based on how much petroleum they can be converted into. Mr.Queequeg's answer only considers conversion to light oil but fails to include the petroleum produced from crude oil.
The recipe for light oil cracking is 30 light oil to 20 petroleum. So 1 light oil is worth 2/3 = ~0.667 petroleum. If you use productivity modules for a 30% bonus then 1 light oil is worth ~0.867 petroleum.
For heavy oil cracking it's 40 heavy oil to 30 light oil. So 1 heavy oil = 0.75 light oil = 0.5 petroleum. With productivity modules that becomes 1 heavy oil = 0.845 petroleum.
Advanced oil processing is 100 crude oil to 25 heavy oil, 45 light oil, and 55 petroleum. So 1 crude oil = 0.25 heavy oil + 0.45 light oil + 0.55 petroleum = 0.975 petroleum. With productivity modules that becomes 1 crude oil = 1.496625 petroleum.
So without productivity modules heavy oil is the least valuable and crude oil the most valuable. Though with productivity modules light oil comes very close to being as valuable as heavy oil.
If you use 1 light oil in your turrets you lose out on ~0.667 (or ~0.867 w/ productivity modules) petroleum and you'll need to pump ~0.684 (or ~0.579) crude to replace that. If you use 1 heavy oil in your turrets you lose out on 0.5 petroleum (or 0.845) and you'll need to pump ~0.513 (or ~0.565) crude oil to replace that. If you use 1 crude oil in your turrets then obviously you'll need to pump 1 crude oil to replace that.
The there's also the damage bonus to consider. Putting it a in a table:

Oil type
Petroleum equivalent
Crude equivalent (via petroleum)
Damage multiplier
Crude / damage

Light oil
~0.667
~0.684
110%
~0.622

Light oil w/ prod 3s
~0.867
~0.579
110%
~0.526

Heavy oil
0.5
~0.513
105%
~0.488

Heavy oil w/ prod 3s
0.845
~0.565
105%
~0.534

Crude oil
0.975
1
100%
1

Crude oil w/ prod 3s
1.496625
1
100%
1

So purely from an economical perspective, heavy oil is usually ideal. If you have tier 3 productivity modules in all of your refineries then light oil comes out just ahead of heavy oil once you account for the damage bonus. That being said, since the damage dealt by flamethrowers is somewhat unpredictable (due to splash damage and fires that stay on the ground) the 'crude per damage' metric is not very accurate. So it's possible that heavy oil still comes out ahead. Either way, it's very close between the two. These conclusion holds even if you care only about crude oil production, not petroleum consumption, as long as your crude oil production is primarily determined by your petroleum consumption (as it is in most bases).
From a logistical perspective, crude oil is the easiest to use since you don't have to refine it first. Moreover, if you move heavy or light oil to remote outposts for defence (using trains) that might in some cases cause a shortage of heavy/light oil in your main base while your petroleum is full. If this happens your oil processing is blocked and you are unable to produce more heavy/light oil to fuel your turrets. This is probably a rare edge case, but if flamethrower turrets are your main defence it is worth considering.
So in conclusion:

Heavy oil is the most economical in the early game.
Light oil is probably slightly more economical than heavy oil if you have full level 3 productivity modules in all of your oil refineries once you account for the damage bonus. Though heavy oil is still a very close second. And given that damage output from flamethrowers is somewhat unpredictable, heavy oil might still come out ahead sometimes.
Cruse oil is the least economical and does the least damage but is the simplest in terms of logistics.
Comment: Under different cost metrics, the best is different. OP asked for least crude, not least petroleum equivalent.
Comment: @Caleth assuming your crude production is primarily determined by petroleum consumption (which it is for most factories), then using the least petroleum equivalent will lead to using the least crude.


What would be the disadvantages of a TTIP?

Question: Well the question kind of says it all, what I would like to know is,if a TTIP between America and EU is put in place even though not only Europe and America will benefit from it but also other countries who export to Europe and America because of the augmentation of demand, would there be any drawbacks for consumers? I know that some companies will find it hard to compete with others but then again what could that cause for us consumers ?
Sorry for my bad English its been a long time.
Comment: Most of the current debate in European countries is not so much about trade - we all know trade liberalization yields welfare gains. It is mostly about the legal power that firms get. US american firms could sue France for french regulation at US courts. This downside is off topic here.
Comment: well that goes more in to politics, but from an economic point of view what would that lead to ? Mostly that the TTIP would mostly be in favor of the corporations but where would that put an average worker ?
Comment: @FooBar, I think what you wrote could be an answer. Very succinct. The big disadvantage of a FTA or a partnership is that there may be a change in how some things are addressed, like property rights.
Answer: TTIP is a combination of trade agreements and property rights / legal changes.
Trade Liberalization
Most of the current debate in European countries is not so much about trade - we all know trade liberalization yields welfare gains. In the first-order, these are split between consumers and firms: Consumer get a larger variety / cheaper goods, and (surviving) firms can reach more customers.
These are efficiency gains, and could be split up anyhow between these two groups. To the extent that surviving firms get some of these welfare gains, workers of these firms might get some of the benefits. I'm trying to be very cautious here, because on this last bit, I don't think we have sufficient empirical evidence - and theory will support different results based on the wage setting mechanism.
Of course, there will be firms that lose, and workers that will be fired - which is why the US has set up (I think under WIA) Trade Adjustments Assistance for workers who lost their jobs due to trade. This is one way of sharing the welfare gains of trade with those who lose.
Copyright and Regulation
The issue with TTIP is mostly the legal power that firms get. US american firms could sue France for french regulation at US courts. This downside is off topic here. However, the angst here is that is not welfare gains for each single country. Countries with stronger regulations will lose. Even for the world as a whole, it is unclear whether this yields efficiency gains, or whether firms just reap surplus from countries/governments.


Multiplicative order and powers

Question: Let's consider two number $a$ and $b$ such as $gcd(a,b)=1$. Can you explain me intuitively why there exist $n>0$ such as $a^{n} \equiv 1 \space (mod \space b)$
 ?
Comment: If you start looking at powers of $a$ you'd eventually start getting repeats when considering the result modulo $b$, say $a^x$ and $a^{x+y}$ both resulting in $z\pmod{b}$, but then $a^xa^y\equiv a^x\equiv z\pmod{b}$.  Try to reason that $a^y\equiv 1\pmod{b}$, using the fact that $a$ is coprime to $b$ and so $z$ is as well.
Comment: Why should we care that $y<b$?  From what I wrote alone, no you cannot, but you can add a few additional conditions... changing the opening statement to "*If you start looking at* **the first $b$ powers of $a$** *you'd eventually start getting repeats...*"  We know that we'll get repeats because of the pigeon-hole principle, us having at most $b-1$ holes (*since it is impossible for $a^x \equiv 0\pmod{b}$*) and having $b$ pigeons.  This guarantees that $1\leq x<x+y\leq b$ and so $1\leq y\leq b-x<b$
Comment: At this point, can we infere that $y<b$ ? If yes how ?
Comment: Thanks so much, if you post i vote your answer as the correct one
Answer: Sure:

Exponents don't cause a change in gcd.
There are finitely many remainders possible.
There are, therefore, repeated remainders are forced after a certain point.

A proof of Fermat's little theorem I once saw is as follows:
Let A, be the set of all products of a, and one of the natural numbers less than b (b in this case is prime, and $\gcd(a,b)=1$). Any of these giving same remainder on division by b, implies  that the two natural numbers a was multiplied by, are congruent mod b. This of course is impossible.
The product of all elements of set A, is: $$a^{b-1}(b-1)!$$ and the set of all non-zero remainders is forced to occur in this set by the above argument, so $$a^{b-1}(b-1)!\equiv (b-1)!\bmod b$$ which turns into:$$a^{b-1}\equiv 1\bmod b$$ when you cancel the factor of factorial on both sides.
It then follows using $$1^r=1$$ and it's equivalent in modulo that all multiples of $b-1$ , as exponents are 1 mod b . These combine in the composite cases.

Multiplicative order and powers


OpenWRT BusyBox init does not create /etc/init.d/rcS

Question: I'm building an OpenWRT image (Chaos Calmer) that needs BusyBox to be configured to use init. So, in the busybox configuration, I enter the Init Utilities menu, then enable init, as well as support for reading an inittab file.
When my image finishes building, it contains the following /etc/inittab file:
::sysinit:/etc/init.d/rcS S boot
::shutdown:/etc/init.d/rcS K shutdown
::askconsole:/bin/ash --login

This looks fine to me, except that /etc/init.d/rcS does not exist. If I load this image onto the router, it obviously fails to boot with the following messages:
init started: BusyBox v1.23.2 (2019-08-29 09:26:36 CDT)
Bad inittab entry at line 3
can't run '/etc/init.d/rcS': No such file or directory

How should this be resolved? Am I supposed to add my own /etc/init.d/rcS? If so, how should that be done (i.e., as its own OpenWRT package)? Is there a standard/default rcS script I can use as a template? Is there a configuration option to include this file that I may have missed? And why does it think the inittab entry on line 3 is wrong?
Answer: It is said , openWrt is using procd for init work. So there is no /etc/init.d/rcS anymore.
Comment: Where is it said, to verify your claim.


what is happening behind the scenes when you buy a cardano nft, from a privte website

Question: I m starting to get into coding, and I did not manage to find an answer to this question.
When you buy an nft you are asked to send an X amount of ada to a wallet, and then few min after the website automatically sends you the nft.
How do I begin to learn how to do it myself?
Comment: The documentation here is a solid way to get started: https://developers.cardano.org/docs/native-tokens/minting-nfts
Answer: I will try to answer this question as there are a few ways this could be happening. So far, I've seen the following

Cardano Smart Contract (most decentralized solution and preferred)
Minting Machine (very centralized and code cannot be verified)
Manually sending

Cardano smart contracts - There is an onchain portion and and off chain portion to consider but in general you can consume a utxo at a smart contract address by simply sending a transaction that meets the contracts parameters for successful validation. When you send ada, you are creating a transaction and submitting it. The smart contract verifies that you have met the requirements and the NFT gets transferred to your wallet. (This is made more seamless with a wallet connector. Connecting a wallet and signing the transaction on the site can trigger the submit and execute the smart contract)
Minting Machines - I've seen a lot of these around and I don't like them as they are not really part of of the blockchain. It's a bash script that gets executed if it detects a deposit of ada coming into an address. Some of the ada that comes in is used to build a transaction to mint the nft. Then another transaction to send the nft to the buyers address is created and sent to the original sender.
Manual - As a developer, I've gotten request to do this manually until they build out one of the other options listed above. My recommendation is to learn the cardano-cli and try some transactions on a node. Then learn haskell and plutus to build smart contracts.
Comment: Per his description, I think he means the second option (minting machine), since he sends X amount of ADA to an address, instead of consuming a script
Comment: And with smart contracts you lose a critical feature: you know exactly what NFT you are buying, so there is no randomness behind the scenes


insert value from sharepoint list to SQL table

Question: I have list with approx 20000 items, and want to push that into sql table. Can anyone help me with c# code. Thanks
Comment: Please share your work. What you have tried so far ?
Answer: A simple solution will be to export the SharePoint list in excel and then import that data into SQL table using SQL management studio,
But still if you want to go by C#, then you can get all list items using below code and then insert into SQL table
<code>using ( SPSite site = new SPSite ("http://moss/sites/yousitename"))
{

  SPWeb myWeb = site.OpenWeb();
  SPList target = myWeb.Lists["YourListName"];
  SPListItems items = list.Items;
  myWeb.Dispose();
 }
</code>
for more information check this link: https://social.msdn.microsoft.com/Forums/en-US/5d61926a-9a18-422f-a34a-dda3e8b3eab1/how-to-export-data-from-a-sharepoint-list-to-a-sql-database


How can I wipe an existing Windows partition, then reinstall Windows as a dual boot with Ubuntu?

Question: So I already have a dual boot of Ubuntu and Windows, but my install of Windows has amassed too many problems and hangs at startup, so I'm going to be reinstalling it. I have a TB hard drive, and about 660GB is allocated to Windows and 210GB to Ubuntu. I already backed up the stuff I need on the Windows partition. I was wondering if there's a way I could wipe the Windows partition to make it unallocated space, then resize Ubuntu to be 660 and reinstall Windows with a 210GB allocation? I'm also a bit concerned that reinstalling Windows will get rid of my grub boot screen. Any help would be appreciated!
Comment: so you want to keep your Ubuntu as it is, increase the size and want to wipe windows partitions and reinstall. thats fine. can you attach a pic when you are in Ubuntu and open "GParted"? your windows and ubuntu both are in UEFI Boot mode or BIOS boot mode? also is it MBR Partitioned or GPT Partitioned?
Comment: My windows and Ubuntu are in BIOS Boot mode. My hard drive is GPT Partitioned. Here's the picture of my GParted: https://i.imgur.com/6PA6Mcs.png
Comment: as per the attached pic, there is EFI Partition. meaning UEFI Boot mode. what is sda8??
Comment: I think sda8 is a partition I made for debian a long time ago because I wanted to try it out, because debian still shows up as one of the OS I can load my pc to in grub.
Comment: I don't need sda8. My Windows version is Windows 10, but my pc came pre-installed with windows 8. I also thought I have BIOS boot because the dual boot screen looks like this person's:  https://www.sevenforums.com/attachments/hardware-devices/339618d1486631026t-cant-enter-bios-when-booting-win7-ubuntu-linux-dual-boot-system-imag0320.jpg
Comment: My windows version is windows 10, but my pc was pre-installed with Windows 8, I upgraded it.
Answer: assuming you are with UEFI boot mode.
it is better to take the backup of your Ubuntu data also as extending ext4 / partition in GParted will take much time.
boot with bootable USB and logon to live session of Ubuntu.

Open GParted.
leave the sda2 EFI partition as it is.
delete the sda1, sda3, sda4 & sda5
now proceed with go signal to write the changes in GParted.
select sda9 and increase its size, it may take long time in live session.
after the completion of process. reboot the system.
Open GParted again, run in terminal sudo sgdisk -s /dev/sda to sort out the partitioning numbers.
make the unallocated space into NTFS file system.
shutdown the system.
boot with windows10 bootable USB. and do the regular installation.
Once windows is installed, it will directly boots to windows. you need to reinstall Grub.
in windows10 turn of fastboot and secureboot.
boot in live session of Ubuntu and then follow this highly voted Q&A How can I repair grub? (How to get Ubuntu back after installing Windows?)


Order of reduction of infinite order rational point on an Elliptic Curve

Question: Let $E/$ℚ be an elliptic curve and $P$ ∈ $E($ℚ$)$ a rational point of infinite order.  Does the reduction of $P$ mod $p$ generate a maximal cyclic subgroup of $E(\mathbb{F}$$p$$)$ for almost all primes $p$?
Comment: No. The primes that split in the field $\mathbb{Q}(Q)$, where $2Q=P$ are counterexamples. One expects a positive density of such primes, but not density one, if $P$ is not divisible over the rationals.
Comment: Already in $\mathbb{G}_m$ the answer is clearly negative, for the same reason that Felipe gave you. The statement on positive density can be proved conditionally on GRH. One can in fact say a lot more in the elliptic case: the group $E(\mathbb{F}_p)$ is the cyclic group $\langle P \mod{p} \rangle$ for a definite positive density of primes $p$, unless there is an obvious global obstruction ($P$ being divisible over $\mathbb{Q}$ or the rational torsion being non-cyclic). Those are elliptic variants of Artin's conjecture; Alina Cojocaru has obtained various interesting results in this direction.
Comment: Thanks for good comments.  I'll write Felipe Voloch's as an answer.
Answer: No.  There is a positive density of primes that split in ℚ$(Q, E[2])$ (where $2Q=P$) and excluding the finitely many primes for which reduction of $E[2]$ isn't injective.  For such primes any maximal cyclic subgroup of $E(\mathbb{F}$$p$$)$ has even order so reduction of $P$ can't be a generator (since reduction of $P$ is 2-divisible).
Answer: However, it is true that $$f_p=\text{order of $\tilde P$ in $\tilde E(\mathbb F_p)$}$$ cannot be "too small, too often." For example, for every $\epsilon>0$, the series
$$ \sum_{p~\text{prime}} \frac{\log p}{p\cdot f_p^\epsilon} $$
converges. (More precisely, the series is ${}\le 3\epsilon^{-1}+O(1)$ as $\epsilon\to0$.)
Comment: That particular result is a special case of one of the main results of:  Murty, Rosen, Silverman, Variations on a theme of Romanoff,
*Internat. J. Math.* **7** (1996), 373-391. Thank you for the kind words about my books. There are also many papers by Murty and others on the elliptic analogue of Artin's conjecture. If you google "elliptic artin conjecture", you'll find some references that will lead you to the literature on the subject.
Comment: @DavidLampert: I believe it is also possible to prove that $f_P > p^{1/3}$ for almost all $p$, though I don't know if this has been written up anywhere. Up to an $\epsilon$ in the exponent, this appears in C. Matthews, *Counting points modulo $p$ in some finitely generated subgroups of algebraic groups*;this is a bit stronger than Theorem 4(b) (with $r = 1$) of the quoted paper. Improving the $1/3$ exponent is an open problem as far as I am aware, though on GRH it is possible to raise it all the way up to $1-\epsilon$.
Comment: Thanks, would you please give a reference and/or a few general words to justify this?  P.S. I enjoy your books on elliptic curves, thanks for them!


alternative to import/export sharepoint 2007

Question: I am trying to export a site with subsites to a new site collection but because I am using hundred of custom features, lists, master pages & relative sharepoint things, I am getting many expection while importing, Looking for a alternative that will just export/import a site without validating anything
Answer: It isn't so much validation as it is basic SharePoint functionality.  Custom Features and such can create any number of custom entities and if those entities do not exist on the site you are attempting to import it into, then it cannot be imported - by definition.  The import/export process does not know how to create the entities, only how to use them.  If you want to import the site elsewhere then you will need to deploy the custom features there as well.  This is especially true of features that create Site Columns, Content Types.
If you are looking for some data-only migration then you may have to export everything to Excel/Explorer and than manually import it into the destination.
Comment: if I am migrating a site to a new site collection which is being created in the same web application, do I have to install all features, master page and other things ?
Cheers
Comment: I thought site collections share things like features, master pages, n that
Comment: That all depends on how the features themselves were scoped but the features will have to be installed *and* activated before it will allow an import


One server sending push notifications to Android and iOS devices

Question: Our organization has an Android app and an iOS app.
We want to start pushing notification to these apps.
Android has GCM.
Apple has APNS.
But we want to create an API which will work on both android and iOS.
What is the easiest way to setup a server so that when a push notification needs to be sent, it knows exactly which server to send the message to?
Answer: I use a service called Parse to do my notification pushes to both Android and iOS. They have great documentation and libraries available. You can get some details here: https://parse.com/products/push
Comment: @Pixel Crunch Is Parse service for push free ? I referred its documentation. In that it was specified that for free account, you have 30 req/s. can you please explain this ?
Comment: Is there any way to do this without using a third party Service?
Comment: Parse Push service is free within 1.000.000 unique recipients.
https://www.parse.com/plans
Comment: @Pepster but i guess we can move Parse code to own server to continue service.
Answer: As a little background this is for a university setting where multiple colleges apps as well as distance education may be using the service. Here is the approach that we are using in our organization.  If you look at the way APNS works it can be used by just sending a web call to the APNS service with the token id.  GCM is very close to the same type of system. Basically create a JSON package and send it to the desired service.
Here is our steps we used to create this service.

Server admins created a server and database that can be called that will collect the tokens from both android and ios devices.  When the device registers we also send what type of device it is.  This is possible since we are just sending data to the database that is has been created.
From here we then created a couple of python scripts that send the data do the desired service whether it is ios or android. These scripts gather the appropriate data from the database and sends the packaged data (JSON package) to APNS for ios message and GCM for google cloud.
We also created a web interface so that those who need to send messages to the devices can.

The rest of the implementation is up to you to decide the best way to utilize the service.  For example when to check for invalid devices,
Because we are planning on using this same server for multiple applications we can send the type of device, token, application, or whatever else is needed for an application to distinguish it from others we produce so that each application that wants to use the service can. I hope this helps and gives you some idea on how to accomplish this.
Answer: For APNS, Maybe you may consider this forked version of PyAPNS that has enhanced message support.
https://github.com/jimhorng/PyAPNs
which means it will catch error response for failure messages and resent the message which are discarded by APNS while sending between failure messages and receiving error response.
Solution:

Non-blocking ssl socket connection to send notification without waiting for response.
A separate thread for constantly checking error-response from read connection.
A sent notification buffer used for re-sending notification that were sent after failed notification, or arbitrary connection close by apns.
(Reference to non-blocking apns pull request by minorblend, enhanced message by hagino3000)

Result:

Send notification at throughput of 1000/secs
In worse case of when 1st notification sent failed, error-response respond after 1 secs and 999 notification sent are discarded by APNS at the mean time, all discarded 999 notifications will be resent without loosing any of them. With the same logic, if notification resent failed, it will resent rest of resent notification after the failed one.

For GCM, you may consider https://github.com/geeknam/python-gcm
For generic wrapper that support both or more mobile provider:
https://github.com/Redth/PushSharp


Silverlight child window getting cropped from edges when resizing browser window

Question: I am using ordinary Silverlight ChildWindow in my application. When resizing the browser window, in particular when making its width smaller than that of the child window, the edges of the child window get cropped, so that it is impossible to close it via the close button as it is no more visible. I have tried a number of workarounds but nothing helped. In particular I have subscribed to the SizeChanged event of the child window and set its sizes relative to the layout root's sizes. Here is the code of the SizeChanged event handler:
// Get the dimensions of the application screen
Size appSize = Application.Current.RootVisual.RenderSize;
// Make the child window occupy the 90% of width and 40% of height of the entire screen
this.Width = appSize.Width * 9 / 10;
this.Height = appSize.Height * 4 / 10;

This code modifies the sizes of the child window, but it also updates the sizes of the overlay, so that it no longer covers the whole page, which is a very strange behavior.
Has anyone encountered this kind of problems? Please share any ideas.
Thanks in advance.
Answer: I had a similar problem. It occured because scale in a browser was higher than 100%.


Multi select files in media browser

Question: I would like to multi-select files in media browser. I came across this sandbox module: Media Multiselect but it has bugs that render it not usable. Does anyone know of a solution to multi-selecting files in media browser?
Comment: And just as i post this I find the patch media_multiselect-update_for_new_media-2216273-32.patch to work, though it does not apply smoothly.
Answer: People are using this patch on latest media to multi-select media files on fields: https://www.drupal.org/node/951004#comment-9681531
Personally I had some problems to make it work at first, but finally I got it working (Had to disable admin_language module).

Multi select files in media browser


Texture "stretching"

Question: New to Blender and my first time using textures. I tried to do a clay-like model but on some parts, the texture is stretching (eyes and legs particularly).
Any idea what I did wrong?
Comment: Want to show how the UV map looks like?
Comment: Updated the post with the UV for the head.
Answer: Have a look at the UV map.
The leaf takes a lot of texture UV space but it's fairly small in 3D space. That way it has a lot of details (=compression).
But the eyes get very little texture space and are big in 3D space. So they have only little texture details (=stretching).
A checkerboard texture can visualize this for you. Ideally, the chess patterns should all be the same size.
You can try to unwrap again with Smart UV Project (What is the difference between Unwrap and Smart uv project?).
Or edit the UV map

scale down the leaf in the UV editor (hover mouse over an UV island and press L to select it).

and try menu: UV → Minimize Stretch. The editor will then try to give the eyes more space (hopefully).
Answer: Let's say you create a very simple mesh:

The automatic UV unwrapping will give a very predictable result:

The mapping can be rotated and scaled so it looks exactly like the mesh (since the mesh is two-dimensional)

Now, the mesh can be modified to represent a box, without changing the UV:

You can notice, that the the texture is not wrapping correctly around the edges:

This is because those edges don't connect on UV map:

But how do you connect them? You can't - not unless you're willing to warp some of those squares into a different shape:

And that's how you get stretching using automatic UV unwrapping. You can strategically mark seams to decrease stretching; here I will completely get rid of stretching, by selecting 4 bottom edges and one of vertical edges, right clicking and choosing "mark seam":

Final result:

In your particular case, you want to add seams in the least visible parts like the back and bottom of the head. You may also just add a seam in a visible spot, but fix the texture later, by copying a fragment near one side of the seam on a temporary layer to the other side of the seam, then painting to hide the differences.
Comment: That is very useful. I haven't messed with uv mapping til now.

Texture "stretching"


Supported options for compiling LibraryLink code with VC++

Question: I have to generate an interface to Mathematica for a fairly large library.  I would like to use LibraryLink, as the generation seems much simpler.  The platform is Windows (VS 2012), and I am wondering what the constraints are with regards to compiler options, etc.  First and foremost: can I compile in 32 bit mode, or does it have to be 64 bits?  (The CygWin toolkit file tells me that MathKernel.exe is a PE32+ executeable, whatever that is, and that the architecture is x86-64, which is 64 bits.)  Would there be any library incompatibilities when compiling with VS2012 (VC11)?  And are there any options I must respect?
Comment: You should have two kernels on Windows: a 32-bit one and a 64-bit one.  By default it'll run the 64 bit one on a 64 bit system.  About LibraryLink: do you need to call Mathematica from another program, or do you need to call that library from Mathematica?  LibraryLink can do the latter, but not the former.  If you need to call Mathematica from another program, you will need to use MathLink.  Also, I *believe* with MathLink it's possible to create an interface which will work with both the 64 and 32 bit versions (you won't need to make two interfaces, like with LibraryLink)
Comment: If you are interested in Windows only, .NETLink is also an option for creating interfaces to libraries.  I just remembered that both the 32-bit and 64-bit versions of .NETLink can be loaded into a 64-bit MathKernel, so that confirms that if you use MathLink (like .NETLink does), then you only need to create one interface that'll work with both kernels.
Comment: We're calling our library from Mathematica.  From what I've seen LibraryLink should be a lot simpler than MathLink to implement.  As for .NETLink, our code isn't managed.  And although we are currently targetting only Windows, in the past, I've had to do more than one port to Unux of code that was only targetting Windows.
Comment: You can use .NETLink to call non-managed code, but I agree with you that for what you want to achieve, LibraryLink is probably the best solution.  This might also be an interesting read: http://mathematica.stackexchange.com/questions/8438/minimal-effort-method-for-integrating-c-functions-into-mathematica
Answer: Use the "TargetSystemID" option to CreateLibrary (this exists for CreateExecutable and CreateObjectFile as well) to compile for a 32-bit or 64-bit target.
"TargetSystemID" -> "Windows" generates a 32-bit binary
"TargetSystemID" -> "Windows-x86-64" generates a 64-bit binary
If you want to use this library from Mathematica, create a Mathematica package MyPackage, and include the dynamic libraries here:
MyPackage/LibraryResources/Windows/MyLibrary.dll
MyPaclage/LibraryResources/Windows-x86-64/MyLibrary.dll

In MyPackage.m, point to the library mylib (the name passed to CreateLibrary):
$LibraryResourcesPath =
 FileNameJoin[{
  DirectoryName[System`Private`$InputFileName],
  "LibraryResources",
  $SystemID
}]

If[FreeQ[$LibraryPath, $LibraryResourcesPath],
    PrependTo[$LibraryPath, $LibraryResourcesPath]
]

$MyLibrary = FindLibrary["mylib"]

Now you can call LibraryFunctionLoad on $MyLibrary.
Comment: I don't want to compile my library from Mathematica; it is a large, existing library, already embedded in Excel, Python and Java.  It consists of about 20 DLLs, and is developed in Visual Studios.  I need to know what the constraints are on the compiler options I use in Visual Studios.


PHP not parsing 1000, 10000, 100000, etc. **Fixed**

Question: I am using the following code to take HTML $_POST vars [type:text] representing min & max price, sanitize and strip "$" and ",", commit them to $_SESSION and then use them for a MySQL query against data in a column of type "Float". The code is as follows...
<code>//The locale I'm using
setlocale(LC_ALL, 'en_US.UTF8');

//The minimum price is handled
//Sanitized POST var to SESSION var
$_SESSION['minprice'] = filter_var($_POST['minprice'], FILTER_SANITIZE_STRIPPED);
// Strip currency symbol and commas
$_SESSION['minprice'] = str_replace(array(',','$'),array('',''),$_SESSION['minprice']);
//SESSION var to local float var for SQL query
$minprice = floatval($_SESSION['minprice']);

//The same is done for the maximum price
//Sanitized POST var to SESSION var
$_SESSION['maxprice'] = filter_var($_POST['maxprice'], FILTER_SANITIZE_STRIPPED);
// Strip currency symbol and commas
$_SESSION['maxprice'] = str_replace(array(',','$'),array('',''),$_SESSION['maxprice']);
//SESSION var to local float var for SQL query
$maxprice = floatval($_SESSION['maxprice']);

//The SQL query
$sql = 'SELECT * FROM tablename WHERE ';
$sql .= "zip like '$searchzip%' "; //Ignore this
$sql .= "&& sellprice >= '$minprice' ";
$sql .= "&& sellprice <= '$maxprice' ";
$sql .= "ORDER BY id DESC";
</code>
$minprice and $maxprice are then compared to a value from the MySQL table and the result is handled accordingly, basically $minprice <= $sellprice <= $maxprice.
For the variable $sellprice = 12.01, the following search queries will return rows from the MySQL database:
The following returns rows wonderfully.
($minprice, $maxprice)
0, 13
0.00, 13.00
$0.00, $13.00
$10.00, $12.02
$0.00, $12111
$0.00, $82711
The following will not return rows, don't know why.
($minprice, $maxprice)
0, 100
0, 1000 - 1000000 and beyond
0, 1,000 - 1,000,000 and beyond
0, 111 // I thought it was just an issue with 0's or commas being parsed incorrectly
$0.00, $111 - $111111 and beyond
10, 11112 //Note that 12111 returns rows above
I must be missing something here, probably something fundamental and silly. I would very much appreciate any help that people are willing to give, thank you.
If you'd like to take a look at the site itself the URL is http://listing.dyndns.org, it's nothing special but it's my beginner's project.
Edit0: There is only one listing on there currently, search for it in the 99208 zip code.
Edit1: used the expression 'select id from tablename where sellprice >= 0 && sellprice <= 111111.11;' and it returned all the right rows, so I know data in the database is OK. Must be my PHP.
Edit2: Looks like only the numbers before the first comma or decimal are being evaluated against what's in the database. I am so lost.
Fixed: Read a great post on here about the badness that ensues when stories monetary values in a FLOAT column rather than a DECIMAL column. Changed the column type to DECIMAL(9,2) and cast the PHP variables explicitly using (int). Now the values are stored perfectly and doing comparison operations against the database values works great. Hope this is useful to someone.
Answer: setlocale is under php 5.3 deprecated and has no effect when it returns false!


Uncertain volatility

Question: Recently, I have encountered something called "uncertain volatility". Is it a popular concept in QF? Do practitioners use it nowadays? What are its pros and cons compared to e.g more familiar stochastic volatility models?
Comment: https://www.amazon.com/Uncertain-Volatility-Models-Theory-Application/dp/3540426574
Comment: Could you give any references to *uncertain volatility*?
Comment: I don't think it is popular, I never heard about it. But popular is not a synonym of interesting...
Comment: Looks interesting!
Answer: It is definitely used in practice:

It affords a tractable way of pricing in a skew that is easier understood
Avellaneda proves that a derivative priced under any stochastic volatility process that is bounded by (sigma_min, sigma_max) will produce a cheaper price than under UVM
It is easily implemented into any PDE pricer at no calc time cost

Edit: just to challenge myself on third bullet point. Given how UVM has two vols, if you are using Euler (i.e. conditionally stable, first-order accuracy) you need to use the larger of the vols for the spatial step size to remain stable. This is not ideal for reasons of accuracy.
Rather than move to ADI (unconditionally stable, second-order) which is not simple to implement, i am a strong pusher of ADE (alternate direction explicit) which achieves the same stability and accuracy ADI but with the code- and computation-complexity of two passes of an Euler discretisation. Look up ADE by Daniel Duffy if of interest.
Comment: Implemented it, traded on it and have positions risk managed on it today
Comment: I disagree with the "definitely used in practice" as well. The model supposes the worst outcome possible and the range $\sigma_{min}$, $\sigma_{max}$ is hardly related to any intuitive range. Also the ADI/ADE comments make no sense for a 1 factor non linear PDE. The remark on the spatial step is not related to the implicit Euler scheme, but to upwinding.
Comment: "It is definitely used in practice" Really? I heard of the model but never heard of a bank that implemented it in front office.
Answer: To learn more about these type of volatility models, I suggest you to have a look on this research paper http://math.cims.nyu.edu/faculty/avellane/UVMfirst.pdf.
They provide robust heding of volatility derivatives
Answer: The model is interesting, but rarely used in practice. One main reason is the choice of the range $\sigma_{min}, \sigma_{max}$. As Martini and Jacquier explain in their article The uncertain volatility model,

the price corresponds to the worst-case scenario where the Gamma changes signs exactly when the volatility switches regimes. This will hardly happen for real - even if it could.

The pro is to model the uncertainty of the Black-Scholes volatility directly. For exotics, this will give a much more pessimistic price than the regular Black-Scholes model used with the distinct volatilities $\sigma_{min}$ and $\sigma_{max}$. Wilmott shows a concrete example in one of his articles. The con is stated above.
Comment: The answer above is incorrect. The model is often used in practice.
Comment: I provide a reference backing up a major shortcoming of the model. Another shortcoming is that it does not even capture the smile. I have also interacted with many banks and hedge funds, none used that model. I don't see any evidence from @JamesSpencerLavan to back the claim "the model is often used in practice".
Comment: We obviously work in very different fields then.

Uncertain volatility


I feel lost with my master thesis

Question: When I sit and start writing my master thesis, I write the first couple lines, then I don't know what to write and get stuck.
I feel like I'm not creative enough for writing.
The questions are. How to get around this blockage? How to organize the ideas? How to stay focused? Is this think typical?
Comment: What is your question? Or do you just.want to talk?
Comment: Hi, welcome to the site.  Do you think you can rephrase this to be a more specific question?  As you wrote it, I don't see how we can provide a helpful answer.  If not, talking to your adviser would be a good start.
Comment: Yes, fairly typical.
Comment: Writer's block. Very common. Look for something else to do (go to the library looking for further references, check your experiments, clean up your programs, print out and proofread your current writing, go for an extended walk, ...). Obsessing about it won't do any good, just much harm.
Comment: [Does this question help?](https://academia.stackexchange.com/questions/7656/resources-on-how-to-overcome-writers-block-especially-for-non-native-english-s)
Comment: What you are dealing with is called writer's block. The short advice is to **just write, don't care at all about the quality, do not allow yourself to delete what you wrote and try again.**
Answer: I have to assume that you have done the required research and are now just at the writing stage.
This could be a lot of things. But one piece of advice is to not try to write it from the first word to the last. Work from an outline. Fill in the outline in such a way that it seems like a blurry picture becoming clearer and clearer.
In other words, if you have some idea about methodology, work on that section for a bit. If there is something about the conclusion that comes to you, write that down. Go through whatever notes you have made and add ideas to appropriate sections as you go.
Another technique is to use index cards effectively. Carry them around with you and add new cards or modify old ones as ideas come to you throughout the day. Index cards can be better than a notebook, since they can easily be rearranged and even discarded. As you mine the notes you have, write index cards for the ideas there. Rearrange as necessary.
Ultimately a deck of index cards could, in some sense, represent the entire work.
This isn't the only possible way to attack it, but a piecemeal approach might be able to help you avoid some forms of writer's block, such as being overwhelmed whenever you sit down.
Of course, this method will require heavy editing for continuity as you get closer to the end.

There is a more extreme method that was once mentioned to me by an English professor in an intensive writing course. He had a lot of contacts who were writers of various kinds. He mentioned one person whose method was to "make one page of progress" every day. The person would work until the current manuscript, including revisions, was one page longer than the day before. This results in a short story every three weeks or a novel every year. But, I suspect that it takes a certain sort of personality, somewhat obsessive, to manage that. And one page of progress is not the same as one page of writing. And it was creative writing he was speaking of, not scientific writing.
Comment: @JonasSchwarz, start with only a sentence or two on a card. Don't try to fill it. You can use different colored cards for different kinds of ideas. See this, though it was written for a different purpose: https://cseducators.stackexchange.com/a/1168/1293
Comment: The index card method sounds very interesting, I want to try it some time! Can you give any advice on how elaborate they should be?
Answer: Try to do the easiest parts first.  Not the most important parts.  Not the beginning.  Just anything easy.
This gives you traction and starts to build up some form of a document.  Once you see that, you move on to the next easiest part.
It is AMAZING how well this process works to deal with writers avoidance.
I just had a work PPT that was scaring and depressing me (mental voice telling me over and over "you are shit").  But I made a computer file and saved it (just a save as of another file).  Then I cleared all the slides except title and one content slide.  Then I edited over the title slide and the content slide became an outline.  Then I added my personal bio/intro.
All pathetically easy and in the context of things, low content/value.  But I started to see a document emerge.  Then I added (using cut and paste) slides with very simple titles for each think I might talk about, maybe 12 of them.  Just blank slides with a very short title on top.  Then I picked the easiest of those slides to fill in.  Then I was on my way and before you know it, I had a 30 page PPT, which I even had to be strategic about only covering select parts and using an appendix during an hour talk.
You can use the same process to overcome that inner voice saying "I am shit".

Save and name a Word file. Yes, just this basic step.
Make the title page.  Yes, just this basic step.  But now it is recognizable as the start of a document on your topic.
Using the page break feature, make sections for the different parts of your document (acknowlegement, TOC, TOF, TOT, abstract, intro, Chapter A, chapter B, chapter C, Conclusion, Endnotes).  You don't even need to write any of the content. Just make a page that has "Table of Contents" as words at the top of the page (not even inserting the TOC yet).  OK!  Now you have a verifiable skeleton of your document.  [Don't worry too much about if the topics are ABC or ABCD or 123.  Just slap a very simplistic 5 year old's breakdown of the topic as sections.  There's more than a 50% chance that that stays as the high level structure...but even if not, it is easy to rearrange content in the future once you have something down.]
IF you have any papers (school papers or journal articles) that cover the content you will do, than cut and paste those in.  AS IS.  Yes, you may need to do some pruning, synthesizing, reformatting later.  But for now, if the content of Chapter A roughly corresponds to your paper in Journal of A, than dump it in.  [Use your judgment here, as if the stuff is way afar, than it's just spinach you have to prune later.  But if it is on the topic, copy it.  (You will use citations and comments to cover yourself for re-use of text.  Don't let the plagiarism pedants stop you.)]
Now write the easiest section.  Which is.  The acknowledgments.  Just type that stuff in.  Boom.  You have actually written a section now.  Yeah, it's a gimme.  Yeah, no content on your topic.  But so what.  This is about traction.
Now the abstract.  Everyone will tell you to write that at the end...but this is about TRACTION.  You can go back and edit it EASY.  But that's a simple set of 1-3 short paragraphs.  You can just jot something down.  And it will get you thinking about the topic.  OK.  Now boom, you actually wrote something about your topic.  Go, YOU!!!!
Continue to pick away at it in this fashion.  Always going for easiest first.  Once you have a skeleton with random pieces of meat hanging off of it, you are going...the cadaver will come to life.
If you need to take a break, then go back and do a little editing, wordsmithing of previous parts. But try to keep that light and don't get too diverted.  The main thing is to get chunks of gory meat on the paper.  Don't worry if not perfect.  Just get slabs of stuff on the paper.
Somewhere around 20-50% of the meat down, you'll have traction and know that you are going to create a complete carcass.  And then you will.
And then pretty it up with embalming fluid and rouge and Sunday clothes.
Give it a kiss...and move on to other conquests.

You can do this.  Try my process.
P.s.  This works even if you haven't done "all the research".  Really as long as you've had some heavy immersion/work in the topic such that you can write a lot of the content, it can actually help you break "RESEARCHER'S BLOCK" to write the paper.  I have written good science papers, where I knew that I still had to do some data analysis or run another set of bench experiments or do a graph...but wasn't in the mood.  The act of writing the entire paper (EVEN INCLUDING dependent conclusions of yet to be done experiments/analysis) got me motivated to do the last pieces of research.  And yes, sometimes I even had to modify my "conclusion".
Comment: (+1) for "Try to do the easiest parts first. [...] This gives you traction and starts to build up some form of a document." This reminds me of [Dave Ramsey's](https://en.wikipedia.org/wiki/Dave_Ramsey) strategy for getting out of debt: ["pay off debts in order from smallest to largest, gaining momentum as each balance is paid off"](https://www.daveramsey.com/blog/how-to-pay-off-debt). It's also how I attacked the grading of difficult-to-grade tests --- start with the best students in the class, as easiest to grade, because they made very few mistakes that I'd have to decide how to deal with.
Comment: Thanks, very useful!
Answer: Write any bit in any order and, very importantly, don't worry about how good it is. Writing and editing are different tasks and require different approaches. Switching between them interferes with doing either of them. You can do the organisation later. Sure, it's nice to be able to organise as you go, but a blank page can intrude so much on your thinking that the panic gets in the way.
To get past the initial bit, you might also want to talk instead of write. What I mean by this is to find someone who is willing to listen and simply describe to them what you are doing, why you are doing it, what you found out and why that's interesting. If possible, get them to ask 'why' type questions when they don't understand something. Then write down what you said - one of the advantages of a lockdown is that such talking is probably recordable. If you don't have anyone, then imagine someone and record your explanation to your imaginary colleague.
Once you have something written, start organising it (not a full edit). For each paragraph, write a few words next to it to describe the main idea. Then look at all those main ideas and put them in the right order by reordering your paragraphs. Work out what ideas are missing, add in a few words for that main idea (in the right place). Expand any into paragraphs that you can, but don't worry if you just leave it as the idea place holder.
There are also resources available, this is a very common problem. Maybe your university has some online recommendations (look for a study skills site). But other universities will also have recommendations.
Another option is to find an extended article on a topic that is like yours. Then simply copy the structure. Obviously you don't want to be plagiarising or using their phrasing, but if they have three paragraphs describing the lab setup, then that gives you guidance on the sort of things you need to put in your description of the lab setup.
Answer: There are some really good suggestions already, but you could also consider getting help in real life. Most universities (in Germany at least, but I'd think the same applies to other countries as well) offer courses to address this problem or have a person one might contact.
From my experience the people providing these services are really competent, but your mileage may vary depending on your institution.

I feel lost with my master thesis