Can we prove, without axiom of choice, that the set of all zero divisors (including $0$) of a commutative ring with unity contains a prime ideal?

Question: Let $R$ be a commutative ring with unity , I know that assuming axiom of choice , if $A$ is the set of all zero divisors (including $0$ ) then it is a union of prime ideals so it contains a prime ideal . Can we prove , without choice , that the set of all zero divisors(including $0$ ) of a commutative ring with unity contains a prime ideal ? Is it equivalent with axiom of choice ?
Comment: You should at least assume that the ring has prime ideals, or any axiom that shows existence of prime ideals, c.f. [this, e.g.](http://mathoverflow.net/q/98549/15782).
Comment: @Ben : But does the fact that the set of all zero divisors is a union of prime ideals follows from cohen's result from multiplicative sets ?
Comment: Yes, it does. The subset $S\subset R$ consisting of all the non-zero divisors is closed under multiplication and contains one. Since any zero divisor $r\in R$ generates an ideal $Rr$ disjoint from $S$, Cohens theorem gives a prime ideal $\mathfrak{p}\subset R-S$ containing $r$. Thus, the set of all zero-divisors is the union of all these primes.
Comment: @saundev you are disregarding the use of cohen's lemma since it uses the axiom of choice, right? Actually, it may be the case that cohens lemma is equivalent to something weaker....
Answer: The comment of rschwieb made me think it's time put everything together.
The statement

A) The set of zero divisors of a commutative ring is the union of prime ideals.

requires the existence of prime ideals in any commutative ring.
According to this MO answer, prime existence is equivalent to the boolean prime ideal theorem (BPI for short).
Since there are models of ZF where there are rings without prime ideals, whilst BPI is weaker than the axiom of choice, the best we can do is prove A in ZF+BPI.
The same MO answer also gives a reference according to which in ZF+BPI also the following holds:

B)  Let $A$ be any commutative ring, $S\subset A$ a multiplicative closed subset (containing $1$), and $\mathfrak{a}\subset A$ an ideal disjoint from $S$.
  Then $\mathfrak{a}$ is contained in a prime ideal $\mathfrak{p}\subset A$ which is disjoint from $S$ too.

This, however, is enough to conclude A, as shown in the comments. Let me recall the argument shortly, for sake of completeness.
The set of non(!)-zero divisors $S\subset A$ contains $1$ and is multiplicative closed. Furthermore, any zero divisor $a\in A$ generates an ideal $Aa\subset A$ disjoint from $S$. By B, there is a prime ideal $\mathfrak{p}$ disjoint from $S$ and containing $Aa$.
Therefore, the union of all prime ideals $\mathfrak{p}\subset  A$ disjoint from $S$ is all of $A-S$, the set of zero divisors in $A$, as desired.


Why doesn't a %en0 suffix work to connect a link-local IPv6 TCP socket in Python?

Question: A week or so ago someone on StackOverflow asked why their Python code for connecting to an IPv6 link-local address wasn't working, and I replied that since it was a link-local address they needed to add a %en0 (or whatever the desired local-interface-name is) suffix to their target IP address.  I thought I knew what I was talking about, so I didn't actually test my suggestion before answering (shame on me!).
Today I went to use that same technique for myself, only to find that it doesn't seem to work.  :^(  That is, this code does not work:
>>> from socket import *
>>> s = socket(AF_INET6, SOCK_STREAM)
>>> s.connect(('fe80::21f:5bff:fe3f:1b36%en0', 2001))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1, in connect
socket.error: [Errno 65] No route to host

The following code, on the other hand, DOES work (with or without the %en0 suffix):
>>> from socket import *
>>> s = socket(AF_INET6, SOCK_STREAM)
>>> s.connect(('fe80::21f:5bff:fe3f:1b36%en0', 2001, 0, 6))
>>>

... but I don't like doing it that way, because in order to figure out which scope ID integer to supply for the last argument, I have to execute a bunch of not-very-portable code to iterate over the local interfaces list, find the interface named 'en0', and extract its scope ID, which is more complexity overhead than I'd like to have.
Given that connect() is accepting the %en0 suffix to the IP address, why isn't it actually using it as expected to determine the scope ID?
FWIW, I am testing with Python 2.6.1 under MacOS/X 10.6.4.
Comment: In Windows, the local bound NIC's scope ID takes precedence over the one you supply in the target address. :(  If you don't intentionally bind the socket first, then the system chooses a NIC to use.  The target scope id is a **hint** only.
Answer: This is the correct way to do an ipv6 connection:
>>> addrinfo = getaddrinfo('fe80::225:ff:fecd:5aa0%en0', 2001, AF_INET6, SOCK_STREAM)
>>> addrinfo
[(30, 1, 6, '', ('fe80::225:ff:fecd:5aa0%en0', 2001, 0, 4))]
>>> (family, socktype, proto, canonname, sockaddr) = addrinfo[0]
>>> s = socket(family, socktype, proto)
>>> s.connect(sockaddr)

getaddrinfo() will return the correct numerical scope and flow information for you.


Creating new page overwrites old page

Question: Every time we add something new, it deletes a previous entry, like its replacing it. Happened with blogs a few weeks ago then sorted itself out, now it is happening with events. Does anyone know why this might be happening?
Answer: Are you using loop before getting content from WordPress? Like this one:
<code><?php if( have_posts() ): while( have_posts() ): the_post(); ?>

You content goes here

<?php endwhile; endif; ?>
</code>
Comment: Not sure how this would address the issue? Your comment appears to refer more to retrieving posts... My issue is with creating posts, and having older posts overwritten after it is created.

Creating new page overwrites old page


Best Practice for Oracle SGA and PGA Memory Components Size

Question: I have a Server that has 128GB RAM. I have read here and there that the size of SGA + PGA can bee 80% of the RAM.
I wonder if there is any best practice for this configuration that could allow Oracle Database to utilize hardware even better?
There is also this consumption that this server will be used only to serve the Oracle database.
Comment: I am using Oracle 11g. and AMM is not an option because experience showed that it does not work well when there is a large memory.
Answer: What version of Oracle are you using?  Are you actually setting values for the SGA components and/ or the PGA separately?  If so, why?  If you're using a recent version of Oracle, the starting point would normally be to set memory_target and let Oracle size the various memory components automatically.  Unless, of course, you have some reason to need to set minimum values for certain memory components.
As for what to set memory_target to, you just need to leave enough memory for the OS and any other processes that need to run on the machine (including things like any backup manager you might be using, any monitoring software that runs on the server, etc.)  It seems unlikely to me that you'd need 20% of 128 GB for that software.  I'd guess that 8 GB would be more than enough leaving 120 GB for Oracle's memory_target.  You could do better than guessing by taking a look at the actual memory utilization on the server over time.
Comment: Oracle seems to have two mutually exclusive 'recommendations'.  First, they recommend the use of Automatic Memory Management (setting memory_target).  But on Linux they strongly recommend using OS hugepages, which cannot be done if using AMM.
Comment: "If you're using a recent version of Oracle, the starting point would normally be to set memory_target" - I don't think that's true anymore.  I had success doing that with 11g, but since 12c Oracle [doesn't allow automatic memory management anymore if the system has 4GB of RAM](https://docs.oracle.com/en/database/oracle/oracle-database/12.2/ladbi/about-automatic-memory-management-installation-options.html#GUID-38F46564-B167-4A78-A974-8C7CEE34EDFE), which effectively makes the feature pointless.
Comment: I am Using Oracle 11g.
when you have a large memory size AMM is not working good enough, and when you need to use hugepages you must disable AMM and use ASMM (Automatic shared memory management). so I have to Set SGA_TARGET and  PGA_AGGREGATE_TARGET separately.
Answer: While AMM seems to work fine, as others have pointed out if you are using Linux, you will save a consiferable amount of memory if you use HugePages. This means that you can't use AMM. You can test what that value will be with AMM and no huge pages for a given SGA/PGA and you can test the same with HugePages and a similar SGA/PGA. If you are on Linux and your SGA is larger than 10G, then HugePAges makes sense.
$:~ > cat /proc/meminfo | grep -i PageTables
PageTables:       282712 kB

Comment: Thanks for the answer and you are right about HugePages. but the main question is about the proportion of SGA/PGA with the available RAM.
Comment: I usually allocate 80% of my memory to the database. So if I was asked to size the SGA/PGA, my swag would be 30GB PGA/70GB SGA. Within the SGA I would have about 10GB shared_pool, 65GB db_cache_size, leaving a few GB for large_pool_size, java_pool_size, steams_pool_size, etc. Whatever else seems relevant. I have a similar sized SGA and I have 60,000 huge pages total, 10,000 of which are free.


Invoke-WmiMethod : Access denied when sending message to EC2 instances

Question: I have a PowerShell script that stops all running instances, I want to add a message that pops up inside the instance to notify the user that the instance is shutting down and if possible accept or deny that.
This is the complete code (as of right know only stops):
<code>Get-EC2InstanceStatus | Out-File -filepath C:\Users\AGOJSO\Desktop\xd.txt
select-string -path "C:\Users\AGOJSO\Desktop\xd.txt" -Pattern 'i-.*$' | select line | out-file "C:\Users\AGOJSO\Desktop\xaxa.txt"
(Get-Content C:\Users\AGOJSO\Desktop\xaxa.txt) | ForEach-Object { $_ -replace 'InstanceId       :' } > C:\Users\AGOJSO\Desktop\xaxa.txt
(Get-Content C:\Users\AGOJSO\Desktop\xaxa.txt) | ForEach-Object { $_ -replace 'Line' } > C:\Users\AGOJSO\Desktop\xaxa.txt
(Get-Content C:\Users\AGOJSO\Desktop\xaxa.txt) | ForEach-Object { $_ -replace '----' } > C:\Users\AGOJSO\Desktop\xaxa.txt

foreach ($line in [System.IO.File]::ReadLines("C:\Users\AGOJSO\Desktop\xaxa.txt")) {
    Write-Host "$line"
}

$instanceIDArray = "i-0159d9e5a717cfb73", "i-012fef2b144ea0476"

( (Get-EC2Instance | ? { $_.instances.tag.value -match $instanceIDArray} ).Instances).InstanceID | Stop-EC2Instance $instanceIDArray
</code>
So now I need to interact via message with the user, I have tried it with this code with no luck, only works if I type localhost intead of the @IP:
<code>$name = "10.115.106.46"
$msg = "Enter your message "
Invoke-WmiMethod -Path Win32_Process -Name Create -ArgumentList "msg * $msg" -ComputerName $name
</code>
Error received:

Invoke-WmiMethod : Access denied. (Exeption HRESULT: 0x80070005 (E_ACCESSDENIED))

Thanks (:
Answer: This is not unique to what you are doing with AWS instances. WMI security can get a bit finicky.
Well, that and The big drawback to the WMI cmdlets is that they use DCOM to access remote machines. DCOM isn't firewall friendly, can be blocked by networking equipment, and gives some arcane errors when things go wrong.
Which is why in in the last few releases of Windows, CIM is being pushed.
Since PowerShellv3 CIM was the focus (it uses WSMAN vs DCOM) (PSv2 and below was all WMI), though many still continued to use WMI out of habit or the need to support v2 or below.
Even with MS Online, it's all PSCore (so learn to use it as well), and CIM focused. So, try and use Invoke-CimMethod instead.
So, give this a shot using Invoke-CimMethod instead of Invoke-WmiMethod, since DCOM requires additional host and firewall configurations in many cases.
See details on this error code here:
WMI troubleshooting
Access Denied errors that are reported by scripts and applications that access WMI namespaces and data generally fall into three categories. The following table lists the three categories of errors along with issues that might cause the errors and possible solutions.
0x80070005 – E_ACCESS_DENIED
Access denied by DCOM security.
The user does not have remote access to the computer through DCOM. Typically, DCOM errors occur when connecting to a remote computer with a different operating system version.
Give the user Remote Launch and Remote Activation permissions in dcomcnfg. Right-click My Computer-> Properties Under COM Security, click "Edit Limits" for both sections. Give the user you want remote access, remote launch, and remote activation. Then go to DCOM Config, find "Windows Management Instrumentation", and give the user you want Remote Launch and Remote Activation. For more information, see Connecting Between Different Operating Systems
Comment: Allright I'll give CimMethod a shot, thanks for the thorough explanation.


Can I legally own and fly fighter jets in the UK?

Question: I've seen a similar post, but it applied to America. Could I own and fly a BAE Systems Hawk T1 in the UK? What kind of regulations are there? Obviously it would have to be unweaponised but I was just wondering about the specifics.
Answer: I don't know of any privately owned Hawks, but there are many ex-RAF jets in private ownership, like the Jet Provost, Lightning, Gnat, Meteor, Vampire, and others I can't remember. The Ministry of Defence sells fixed-wing airplanes and helicopters occasionally at auction; when they retire the Hawk T1 you could be able to pick one up.
This CAA document goes over many of the particulars, a quick summary is that in almost all cases they would be under a permit to fly. This would require an inspection to clear it for the permit, and an (un)healthy dose of paperwork. I know of no way to get these aircraft certified, but you can get them cleared for night and IFR flight with extra paperwork and continued inspections, provided the aircraft is equipped for it. You can also get a permit to fly faster than 250kt below 10,000ft, which in a jet like the Hawk would be an advantage. Flying abroad on a UK permit aircraft is just more paperwork: you have to get permission from all the countries you'd fly over and land at, which is generally a formality, and restricted to day VFR.
One of the challenges you would find is keeping the plane airworthy. There are a few organizations that restore and maintain ex-military jets; you'd want to find out if they'd be able and willing to take it on for you before you buy it.
Of course you'd also need an awful lot of money. Jet Provosts (50s era trainers) are at the low end of jets as costs go and they still cost £600 per hour to operate!
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/116627/discussion-on-answer-by-gdd-can-i-legally-own-and-fly-fighter-jets-in-the-uk).


can i limit editing specific custom fields to certain roles?

Question: i am writing a plugin that injects unescaped content (including javascript) into a post. i'm storing this content as a custom field, and am wondering if there are any built in ways to prevent users from editing specific custom fields.
Answer: Simply use a Custom Field with its name starting with an underscore, so it won't show up in the CF meta box, eg, _field_name instead of field_name.
It will be hidden for all roles, but if you are manipulating its value only through code, then no problem.
If you need to manipulate the value on the edit screen, then you'll need a Custom Meta Box and control its appearance according to the user role.
[ update: looks like this kind of field can only be entered dynamically, it dumps an error if you try in the admin interface ]
Comment: very cool thanks! and your update suggests a user cannot update this field even with a special request, so i don't have to worry about users being able to write their own XSS-y scripts in that field
Comment: I'm not finding the documentation about this feature, but I'd risk to say that yes, you don't have to worry about users messing with it.
Comment: i found it after reading your answer: http://codex.wordpress.org/Function_Reference/add_post_meta#Making_a_.22Hidden.22_Custom_Field
Comment: @PETER, thx, added the link to the Answer.
Answer: Without code, it is hard to give you anything specific. A lot depends on what you are doing and where you need to do it.
In addition to what brasofilo suggested, you can always wrap individual blocks of code with current_user_can. For example...
if (current_user_can('administrator')) {
  echo "You are awesome";
} else {
  echo "Ha! Ha! You can't do stuff";
}

Note: the Codex page for current_user_can warns against using a role name, but the source documentation states "@param string $capability Capability or role name". I do not know why they differ and I have never had a problem with a role name, but be aware.
Comment: Nowadays, I use a custom function [`current_user_has_role`](http://wordpress.stackexchange.com/a/77430/12615). If remembering well, I had problems with `current_user_can` in the first versions of [this A](http://wordpress.stackexchange.com/a/53714/12615).
Comment: Were you using role names in those functions? The current versions use capabilities.
Comment: Yes, I edited the role names out in favor of capabilities. The whole `*_user_can` issue seems a bit murky...


How do you turn on the fast walking ability on Smart Moving Mod?

Question: I tried to do "O" and "I" but they made only me slower. I'm trying to find out how to go faster not slower.
Answer: Controls
Here is a quote from the Official mod page:

Faster Sprinting and Exhaustion
This mod implements a faster, optional, configurable sprinting and exhaustion  behaviour. It is merged with the standard minecraft sprinting and hunger behavior.
To sprint you have to move forward and click and hold the sprint button (default "TAB"). >Sprinting is currently possible for walking, swimming diving, crawling, and climbing.
  Sprinting optionally causes exhaustion and will automatically end when a certain configurable threshold is reached.
To change this default sprint button visit Minecrafts "Options"/"Controls" menu.

I have bold & emphasized the things probably needed for you.


Incoming Email in SharePoint should have option of opening email from Outlook and reply

Question: I am trying to set up incoming email for a SharePoint Discussion Board, i know for a fact that i can receive emails but is it possible to open the email via Outlook and then be able to reply and next the replied email then needs to be stored back in discussion list again under Replies
Answer: Create a calculated column and set it to return a number datatype. This allows you to enter and run code.
Copy paste the following (enter the actual name of the senders email column):
="Reply"

This will open up the user default mail application (such as Outlook) and automatically have the To field set to the senders email and what ever the inbox is of you sharepoint email address.
This results in a column that creates a link unique to each item. Now you just need to display that column and have your users click on that link.
As for storing it under replies.. You may be able to do something with a workflow based on the senders email (in this case a known SP user) where you set a tick box marking this email as a reply..


MVC 3 Ajax returning partial view of area

Question: I am trying to return a partial view via ajax. My code likes below and it works fine when partial view is not in an area.
[HttpPost]
public ActionResult SearchLogsAjax(string searchParams)
{
    // Do some searching
    return PartialView("LogResults", searchResults);
}

Partial View is rendered when I first open the page. The problem occurs when I press the search button which makes an ajax call to the ActionMethod. If it is in Admin area I get the classic view not found error.
The partial view 'LogResults' was not found or no view engine supports the searched locations. The following locations were searched:

~/Views/Log/LogResults.aspx
~/Views/Log/LogResults.ascx
~/Views/Shared/LogResults.aspx
~/Views/Shared/LogResults.ascx
~/Views/Log/LogResults.cshtml
~/Views/Log/LogResults.vbhtml
~/Views/Shared/LogResults.cshtml
~/Views/Shared/LogResults.vbhtml

Why it is not looking under Admin area which is the current area?
Is there any way for me to specify the area name I wanted, by something like new { area = "Admin" }
On the other hand when I move mouse over the partial view name in the code, ReSharper shows the view which i expected.
Answer: You can specify the area name you want, by using the RouteValuesDictionary parameter and syntax same as you suggested
new { area = "Admin" }

But the trickier part to me is getting the proper method signature (meaning the signature that I intend to be using) because there are more than a couple of choices and it is EASY to get the wrong signature and still be syntactically correct.
In this case I think you want the signature:
public static MvcHtmlString ActionLink(
    this AjaxHelper ajaxHelper,
    string linkText,
    string actionName,
    RouteValueDictionary routeValues,
    AjaxOptions ajaxOptions
)

So modify the Ajax.ActionLink you currently have (which you did not post) to something like this:
@Ajax.ActionLink( "Link Text", "YourAction", "YourController", new { area = "YourArea" }, new AjaxOptions() { *the ajaxoptions you've been using* } )

Hope that helps.


l accidentally permanently deleted a Draft. There's any way I can recover it?

Question: I recently started a blog and I was about to finish my second Post.
I was cleaning up some stuff and decided to empty my Trash. I wasn't paying much attention to it because I wasn't expecting my Draft to be there. I accidentally deleted it. There's any way I can at least visualize it and somehow retype it. Any help would be greatly appreciated.
Answer: No, if you've emptied the Trash you can't recover anything from it (and note after 30 days in trash, a post will be permanently deleted.)
If you have database backups, you can restore a draft from the wp_posts table (look for records with post_status = "draft" and grab the post_content field.
https://en.support.wordpress.com/deleted-posts-and-pages/
Answer: At least in Chrome and Firefox you can enter about:cache and start digging there. With some luck you might still find something.
Unfortunately I can't give you a more detailed instruction as I've never done this before myself. Also if you plan to follow that path you are not too likely to be helped here on WPSE as this isn't a WordPress issue now any more.


X-ray diffraction from crystals and time-averaging

Question: To calculate the elastically scattered intensity of x-rays from crystals, one classically considers scattering from a free electron first and then one sums up the scattered em-fields of all electrons in an atom and eventually in the whole crystals, after which the time-averaged Poynting vector gives an expression for the scattered intensity. For an unpolarized beam with intensity $I_{0}$, the elastically scattered intensity from a free electron in spherical coordinates is given by (Thomson scattering)
$$\begin{split}I(R,\phi,2\theta)=&I_{0}\frac{r_{e}^{2}}{R^{2}}(1-\sin^{2}2\theta\left<\cos^{2}\phi\right>)\\
=&I_{0}\frac{r_{e}^{2}}{R^{2}}\frac{1+\cos^{2}2\theta}{2}\quad\quad\quad\quad\quad\quad\quad (1)
\end{split}
$$
with $\left<\cdot\right>$ the time-average. Now when expanding this to crystals one writes
$$I(R,\phi,2\theta)=I_{0}\frac{r_{e}^{2}}{R^{2}}\frac{1+\cos^{2}2\theta}{2}GG^{\ast}\left<FF^{\ast}\right>\quad\quad (2)$$
with $X^{\ast}$ the complex conjugate of $X$ and $G$ the Laue interference function (wich is zero almost everywhere except for the directions for which Bragg's law holds) and $F$ the structure factor (which depends on time because electrons move in an atom and atoms move in a crystal due to thermal motion). The point is that the time average of $F$ and $\cos^{2}\phi$ are considered separately! But why is this valid? Or in other words, how does (2) follow from (3)
$$I(R,\phi,2\theta)=I_{0}\frac{r_{e}^{2}}{R^{2}}GG^{\ast}\left<FF^{\ast}(1-\sin^{2}2\theta\cos^{2}\phi)\right>\quad\quad (3)$$
Comment: The simple answer is because the F is thermal sampled, and it doesn't change as the photon hits the crystal. But a better answer is that you shouldn't be looking at the derivation in this book, because this is just a hokey classical way of deriving a formula whose only true justification is quantum.
Answer: Not my field, but I hate to see a well asked question like this go without an answer, so I'll take a crack at it.
Firstly, if it works in practice then you have an empirical justification. If it works, it works.
But lets try to see why.
Classical justification
Without actually knowing the answer my first inclination is to ask who the period of x-rays compare to the time scale on which $F$ varies.
If these timescales are very different then you can reasonable hold the slow one as fixed while you average over the fast one, and then average over the slow one in order to determine you experimental response.
Semi-classical justification
Structure functions describe a physics that is largely quantum mechanical in nature. If you don't measure which configuration you scattered off of individually then you should sum over them incoherently. At the same time we continue to treat the E&M classically, so it gets time averaged after the incoherent quantum sum has been taken.
Comment: Yes, I agree, but there isn't any correlation, nor can there be, the photons are independent of the F-changes (even if they were at the same time scale). I don't like the method--- the reason the fellow is getting confused is because he's imaigning a classical EM wave washing over the atoms, as they jostle around thermally. This is annoying, the time-scale difference would be apparent if the book said "photon".
Comment: The x-rays have nothing to do with the varying of F, F is a snapshot of the thermal distribution of nuclear positions, which is essentially frozen on the x-ray scale. I gave an answer, but I _hate_ this derivation, because the only correct way to do photon atom interactions is with a field hamiltonian for photons, and this semiclassical nonsense confuses the heck out of people.
Comment: *"The x-rays have nothing to do with the varying of F" Yes. That's the point. The two variation (in the field and in the structure functions) happen on different time scales so it is safe to neglect any correlation. Of course it is only an effective theory, but it works surprisingly well. Lots of things do.
Comment: Thanks for your answers. I can intuitively understand the time-scale justification, but can this approximation also be expressed mathematically?
Comment: Furthermore, there are actually three time-scales (x-ray, motion of the electron, thermal motion of the atom). So could you say that x-ray time-scale << electron time-scale << atom time-scale? Of course I understand that this really should be treated quantum mechanically, but the fact that the classical approach gives the same result tells us that the approximations made are valid, no?
Answer: The simplest way to say it is that the photon scattering phase is uncorrelated with the crystal nuclear position configuration. The photon comes in and comes out while the crystal is effectively frozen, and the next photon sees a crystal which is effectively the same as the first, until, eons later from the point of view of any photon x-ray process, the crystal has thermally changed. The thermal average is a slow (on x-ray time scale) average as the nuclei jiggle around randomly, and it can be done independently of any fast photon average.
Photon atom Hamitlonian
But this is not a good answer to the confusion you have. The real reason this is confusing is because the book is using an unjustified classical calculation method that happens to give the same answer as the correct quantum calculation. The directional intensity of scattering of a single x-ray photon happens to be derivable from a classical model, because the classical wave is produced from a lot of coherent photons superposed together.
When you are dealing with X-ray photons and atoms, you should use the photon-atom Hamiltonian, assuming the nuclei are classical and the electrons are quantum, and the electron Hamiltonian is nonrelativistic, but coupled to radiation. This is the electron Hamiltonian
$$ \sum_n {( p -eA(x))^2\over 2m} + \sum_i V(x_i) + \sum_{i\ne j} {e^2\over (x_i-x_j)}$$
The field Hamiltonian is proportional to
$$ \sum_\epsilon \int |k| a_\epsilon^\dagger(k) a_\epsilon(k) {d^3 k\over (2\pi)^3} $$
Which is just the sum over modes of the photon energy times the number of photons, and $\epsilon$ is the polarization. This is how you should calculate photon by photon scattering. But the result is equivalent to calculating classical reradiation by free electrons. This is not a coincidence, but it gives you the conceptually wrong picture of what is going on.
The ground state energy of the electron Hamiltonian (ignoring the photons) is the potential energy for the classical nuclei, which you then allow to move classically. The Hamiltonian is used to lowest order perturbations to see the transitions due to the photons in the electrons and to calculate the photon scattering.
You can't use this Hamiltonian to do higher order perturbation calculations (at least not in a reasonable way, without hokey cutoffs at the mass of the electron), because it doesn't allow renormalization. This is because it is nonrelativistic. The photons change the effective mass of the electrons in a relativistically invariant way, but the elecrons are invariant under Galilean transformations, so that if you have a cancellation between bare-mass and mass correction, it doesn't work if the electron is moving at a constant speed. This failure of renormalization means that you get infinities in the higher order calculations, so that this formalism fails to give higher order answers. You need a relativistic theory, or a consistent nonrelativistic truncation.
But this formalism works great to tree order, ignoring loops. The scattering of x-ray photons off the electrons should be calculated this way.
Comment: @Wox: This is also something Feynman does--- it's a really annoying thing that this semiclassical method works, it means that you can write books on x-ray diffraction without saying "photon" which is what is really going on. The averaging is not explained in books. If you have two variables x and y, and P(x,y) is independent probability distribution, so equal to P(x)Q(y) for some P and Q, the average of any function of x times any function of y is the product of the average of each function separately. This is Fubini's theorem in measure theory (iterated integrals are double integrals).
Comment: I will add this to my long list of "things I should learn". But I was wondering, shouldn't one be able to reduce the quantum mechanical approach to the classical approach of oscillating electrons in a classical em-field? After all, they give the same result (I take your word for it, I haven't actually mastered the quantum mechanical approach myself). Or is it more that the classical approach incorporates some leaps that are unjustifiable (like the one we discuss here), just to end up at the right result?
Comment: @Wox: There is no leap in the classical result--- the two averagings are independent, and when you average over independent variables, the averaging commutes. It's like asking "what's the average of the temperature times the stock-market price?" It's the average temperature times the average stock market price, because the two are uncorrelated! You can do the quantum calculation correctly semi-classically, this is what Feynman does in 1950 book "Quantum Electrodynamics" to derive the Feynman diagrams. This classical picture is wrong, because the electrons are not free and not shaking linearly.
Comment: As for the free electrons: this is dealt with in the classical approach by using the damped driven harmonic oscillator model for a bound electron in an em-field, from which the atomic scattering factor follows (included in the structure factor $F$). Of course that is an approximation, but at least electrons aren't considered free.
Comment: But back to the time-averaging. I still have problems to wrap my head around it. Do you have any references where the "independent time averaging" idea is used/explained?


Can I do CAD and rendering work on my Mac by Remote Desktop(ing) to a powerful windows machine? (wired connection)

Question: Ok so my monitor is an Ultrafine and doesn't have any sort of input for a PC. Also, it would be nice keeping the PC away from the desk. Also also, it would be nice doing productivity work on one computer (my Mac) and just hopping between MacOS and the Remote Desktop. The PC is a 7700k with a GTX 1080 ti. I am using it exclusively for Rhino 3D and VRay. How would the performance be if I were to headlessly connect to the PC via my Mac with -say- an ethernet connection?
Comment: Microsoft RDP will restrict the graphics capabilities of the machine - you might be able to do it by having the app running before you connect. I've known things that don't run properly if you connect then run. They detect a 'poor' virtual GPU rather than the real one.
Comment: But why wouldn't a wired connection make everything instantaneous? ..remove all latency
Comment: Latency isn't the issue, the 'fake' RDP GPU is the issue. if an app won't launch, you can't use it. I spend all day, every day with a PC RDP'd to my Mac. if I need GPU-intensive, I have to go to the PC to start the app.
Comment: Thanks for the quick responses! Can I have these apps automatically start upon boot to overcome this issue? Also, would a wired connection make the RDP completely lag free?
Comment: 1) Yes, though specifics are not really my forte on Windows. 2) there's no such thing as lag-free, you're dealing with transmission of a moving 'picture' of the remote screen, not just moving a mouse around.
Answer: The performance of any Remote Desktop connection by the laws of physics and the need to encode the data is always slower than a native display.
So, no, the performance can't be as good with a remote connection adding latency and delay.
That being said - practically, you are always going to be more productive than getting up and moving to another computer and you can get prodigious amounts of work done remotely across a continent let alone across the room. With a decent WiFi connection (say 802.11 ac and less than 10 radios connected to the AP and low interference / SNR above 10 dB ) or any 100 megabit wired/switched ethernet you will have a hard time measuring the delay or worrying about performance. Gigabit ethernet is even better.
I wouldn't worry about this performance loss in practice, you are likely going to be 100 to 10000x times slower than the CPU in all cases, not the remote connection.


Good introductory book on geometric algebra

Question: The title of the question already says it all but I would like to add that I would really like the book to be more about geometric algebra than its applications : it should contain theorems' proofs. Just adding that I have never taken a course on geometric algebra. I'm a 2nd year engineering student, so a "beginner" book style will be very good!!! Also mentioning what would be the prerequisites for mastering the branch is appreciated. Thanks.
Answer: The classic reference is David Hestenes' New Foundations for Classical Mechanics which is by one of the early developers of geometric algebra.
You may find it easier to learn geometric algebra from Geometric Algebra for Physicists by Doran and Lasenby though (I certainly did). The link is to a sample version of chapter 1.
A reference that I've never looked at is Geometric Algebra for Computer Science which details the geometric algebra approach to computer graphics, robotics and computer vision.
As for prerequisites - certainly some familiarity with linear algebra. For the 'geometric calculus' component a first course in multivariable calculus would be sufficient. Since the big developments in geometric algebra in the 1980s were by physicists, many of the examples tend to be physically motivated (spacetime algebras, relativistic electrodynamics etc) and a passing familiarity with (special) relativity, rigid body dynamics and electromagnetism would be useful (though certainly not essential).
Comment: Thanks!! Please have a look at my comment on zyx since you learnt geometric algebra in a physics context. Again thanks a lot for the references!!!
Answer: The previously mentioned "Geometric Algebra for Computer Science" is a good
introduction that concentrates on the algebraic (not calculus related part) of GA.
It does have material on GA's application to computer graphics, but the bulk
of the text is just on the geometry behind GA.
Another possible starting point is "Linear and Geometric Algebra" by Alan Macdonald. This is a text that replaces the standard material of a first Linear Algebra course with the same topics using GA. It is, in my opinion, a great way to learn both Linear Algebra and Geometric Algebra. The text is developed rigorously with theorems and proofs but includes ample examples and motivation. This book also does not try to develop the calculus part of GA.
Comment: This is Alan Macdonald. Thank you for the kind words. For information about my books, see http://www.faculty.luther.edu/~macdonal/laga/ and         http://www.faculty.luther.edu/~macdonal/vagc/
Comment: Just fyi, Alan Macdonald has written a second book "Vector and Geometric Calculus" that does develop the calculus from the perspective of GA. It was meant to be a continuation of LAGA. I find him to be an exceptionally gifted author and look forward to working through it.
Answer: There are different meanings of the words Geometric Algebra.
One is represented by Artin's book on the reconstruction of algebraic structures (fields, rings) from the geometries that they coordinatize.
The other is the use of Clifford algebras, quaternions and related ideas as a formalism for geometry and physics.  This is popularized by Hestenes and is somewhat controversial, not because the math is wrong, but because it uses extra metric structure in cases where not logically required, and because of the tendency to rename known concepts and overstate the differences and advantages compared to the conventional approach.  Using quaternions to represent three dimensional rotations is not controversial at all and is an important method in computer graphics, but this is a different theme of much more limited scope than Hestenes' program to rewrite physics in Clifford algebraic language.
Comment: What do you mean by "because it uses extra metric structure in cases where not logically required"?
Comment: Yes, I'm talking about Clifford algebras. Also i got interested with it because they say it simplifies lot of stuff. Do you think you think Clifford algebras claim more that they can deliver to the physics community? Thanks.
Comment: I found out quite recently that Emil Artin had a book on geometric algebra and was wondering if it had to do with Clifford algebra. Thanks for mentioning the distinction!
Answer: If you are really a beginner, I can recommend this book Geometric Algebra: An Algebraic System for Computer Games and Animation
It has nothing to do with computer animations or games but describes the whole machinery of GA in a clear and CONCRETE manner without obscure formulas and with tables for all products in G2 and G3. He also explains how to calculate intersections of every objects from the standpoint of the usual methods and then shows how to do this in GA, I have never seen this so easily explained in any other book or literally in every pdf I found on the internet. It is also a short book with about 200 pages that can be read in one day. It doesn't cover conformal GA and GA calculus which is a good thing because as a beginner you don't understand it without being familiar with the basics. There are no exercises, but from the examples he gives you can easily make up your own. The book also doesn't use a theorem-proof style concept (actually I think there is only one proof), but again I think as a beginners this is not so important. This should be the standard book for people who want to learn it ! Additionally to that I would recommend that you use the CluCalc Geometric Algebra software for calculating and visualising, it's very easy to learn, for an introduction you can use Google to search for pdfs about it.
Answer: Besides the books by Hestenes, Hestenes and Sobczyk, Dorst, Doran and Lasenby, Porteous, Lounesto, and Baylis, you should find a rather accessible paper by Eric Chisolm on ArXiv.org.  You will find its abstract at the following URL.
http://arxiv.org/abs/1205.5935
I believe that paper meets your criteria for containing the theorems and proofs, as well as a good collection of references.
Answer: I like Porteous's Clifford Algebras and the Classical Groups for a purely mathematical perspective.  Pertti Lounesto's Clifford Algebras and Spinors is also really good and talks about applications to physics.
Answer: This is a late answer, but the book in question wasn't published until 2019.
In my opinion, by far the best book about Clifford algebras and related things is Geometric Multivector Analysis: From Grassmann to Dirac by Andreas Rosén (and I'm not saying that just because I happen to know the author). It is aimed at advanced undergraduates, so it's maybe not completely "beginner style", but he puts a lot of effort into explaining the ideas and the philosophy of the subject, and there are complete and crystal clear proofs of (almost) all the theorems. The book builds the theory from the bottom, starting with exterior algebras and Clifford algebras, and finishing with the Atiyah–Singer index theorem.
Answer: There is the classic book "Algèbre géométrique" ("Geometric algebra"), from E. Artin -if this is the subject about what you're asking. I only know the French version, but it should exist an English translation. About the prerequisites, I think that a first course on Linear Algebra would suffice.
Comment: I looked into the work of E. Artin and I don't think that's the geometric algebra i'm looking for. Thanks
Answer: A recent book, exceptionally clear and rigorous, is: Jayme Vaz Jr & Roldão da Rocha Jr (2016) An Introduction to Clifford Algebras and Spinors.  It gives a thorough grounding for geometric algebras in a way that builds the concepts from the ground up, but does not make the mistake of "hiding" the inner product in the definition and does not define misbehaved operations such as Hestene's "dot product of multivectors".
This book is readable and hence suitable for someone at a 2nd year level, but it is helpful if you are comfortable with the concepts such as vector spaces without magnitudes (a way of comparing lengths of vectors that are not parallel) and the dual of a vector space.
Answer: I found "Linear and Geometric Algebra" by MacDonald exceptionally clear.
https://www.amazon.com/Linear-Geometric-Algebra-Alan-Macdonald/dp/1453854932/ref=mp_s_a_1_1?crid=NM8K3HHV9PCO&keywords=linear+and+Geometric+Algebra&qid=1694625026&sprefix=linear+and+geometric+algebra%2Caps%2C424&sr=8-1
Comment: This book was mentioned in [this highly upvoted answer](https://math.stackexchange.com/a/86218/26369) from 12 years ago.


Merge conflict warning in Visual Studio Code and Salesforce Extension Pack

Question: Currently I'm trying to change from Sublime and mavensmate to Visual Studio Code with the salesforce extension pack. The only thing that holds me back is that I don't know to configure the VS code to check the code in the server before deploying it to avoid code overwriting. You can find this funcionality in mavensmate and in the Intelj plugin.
Does anyone know how to configure the VS code to implement this funcionality.
Thanks a lot.
Comment: What commands are you using / how are you deploying code to server?  I believe this kind of functionality is on the SFDX roadmap, but not available as of Summer '19.  In general, using version source control like git and an online repo should be the model to use as the source of truth moving forward
Comment: I made this same move from Sublime/MavensMate to VS Code/DX at the beginning of the year :-)
Answer: Using the VS Code Salesforce extension pack and their "SFDX: Deploy This Source to Org" command actually uses different deployment methods depending on the org your developing against.
As per Develop Against Any Org documentation, if you're developing against a scratch org (i.e. you set it as your Default org), then it uses the force:source:push command, which indeed checks for merge conflicts. If you're deploying against a non-sourced org, like Sandbox or Production, it uses the force:source:deploy command, which always overwrites whatever is in the org:

The source:deploy command works differently from source:push for scratch orgs. The source you deploy overwrites the corresponding metadata in your org, similar to running source:push with the --force option...

There is a safe harbor statement that Sandbox orgs might get this force:source:push functionality with source-tracking and merge conflict checking, but we won't see that (and probably it'll be in beta) until Winter 20 or after.
Comment: Thanks a lot for the answer, it was realy usefull.
Answer: @Alleren I think this is a major flaw of Salesforce Expansion Pack. There is an issue in github related to that https://github.com/forcedotcom/salesforcedx-vscode/issues/971
This is a big disadvantage of this product comparing to all competitors which have this feature.
It is not possible to configure Salesforce Expansion Pack until this is implemented for the corresponding github issue  so that this issue is fixed
Answer: This isn't an exact answer for your question but it definitely is a way to do what you're looking for,
so if you Right-Click on any file in vscode-dx and you'll have the option

SFDX: Diff File Against Org

A sample use case: You have a sandbox org and a full org (used for staging and QA) and you also have a develop repo which you branch out from and create your feature in the branch. After you're done with your dev and your PR is approved you merge your branch with the develop branch and now it's time to deploy to org and regardless of your deployment method, (creating change-set vs deploy to org using vscode), you'll want to diff to make sure you're not overwriting anything in your full org, so you change your org from sandbox to full in the vscode and I'd also change my repo to develop(since I've already merged my branch) and now on each file I Right-Click and use the SFDX: Diff File Against Org and then deploy the file to org
Just in case you're interested, I'm putting down the link to Salesforce Developer Documentations for Salesforce-DX, there are so many useful information in there: Salesforce DX Developer Guide
I hope this helps,
Cheers!!
Answer: Salesforce Extension Pack for VSC does have beta feature:
https://developer.salesforce.com/tools/vscode/en/user-guide/detect-conflicts

Whenever you retrieve or deploy source to keep the local project and
your default org in sync, the operation could detect conflicts. The
conflict detection feature is available only in non-scratch orgs such
as sandboxes or dev orgs.
If conflicts are detected, you can cancel the retrieve or deploy
operation and view the differences between your local project and
default org.
To view the files that caused conflicts, click the Org Differences
icon () in the Activity Bar. The Org Differences: Conflicts view opens
in the Side Bar and displays the list of files with conflicts. To
resolve conflicts, click a file to open the diff editor and compare
the remote file (to the left) with the local file (on the right). To
edit a file, hover over the file name and click the open file icon.


How make a item visible only for one user inside a site

Question: Hi I'm trying to find a way to make  an specific item  visible for only one specified user of the  site.
Has anybody any idea?
Comment: Is this for security or just a filter?
Answer: You can assigne the unique permissions for an user, but

When there are many unique permissions in a list then it can reduce
  the overall performance of the query so that isn't recommended. The
  number of unique permission in a list gets bigger over time and that
  reduces the performance. While the limit is by default 50,000 it is
  ideal if you make your customized limit 5,000.

see this post.
Answer: Set the permissions of the item to only allow that one specific user access.
This will not prevent Site admins from seeing the item, but that's the best you can do.
In the browser on a view where you have the item select Manage Permissions in the dropdown next to the name. In the permissions page click Stop Inheriting Permissions in the ribbon. Add the user giving her/him the right rights. Remove all other users/groups.
Answer:
Break the permissions inheritance for the list that contains your
item.
Clear, then set unique permissions for the item. Either do this
for the specific user, or use a SharePoint group that only
(initially) contains that user.


Is it bad practice to in a REST API to use Form Data in POST requests when all responses are in JSON?

Question: When developing a REST API, is it ok to use Form-Data in POST requests or is that frowned upon? All my methods return a JSON body or only an HTTP code, should this be extended to my POST and PUT requests as well? I think that Form-Data is a lot easier to work with, but that might just be that I'm a bit new to developing REST APIs.
Comment: If you want to strictly conform to REST semantics, you will only use POST for those things that aren't covered by a GET, PUT or PATCH.  However, most applications don't require this level of rigor.  I have worked for companies that have successfully created APIs using only POST, and the APIs of many large companies are not fully REST compliant.
Answer:
When developing a REST API, is it ok to use Form-Data in POST requests or is that frowned upon?

The ur example of REST is the world wide web, where we posted application/x-www-form-urlencoded documents to the server and received text/html responses.
So decoupling the request representation from the response representation should be fine.
From a REST perspective, the more interesting question is "how does the client know which key value pairs to include in the request body?"  On the web, we have HTML forms, which allow you to describe to a general purpose component how the request payload should be constructed.  Without that piece, if you are using out of band communication to tell bespoke clients how to create the request payloads, then you aren't really doing REST.
(Which, by the way, is fine -- if you don't need the REST properties, then you can relax the corresponding constraints.  Document exchange protocols described out of band isn't the REST architectural style, but it can get the job done.)
Answer: I don't think so. REST API != JSON API.
However, you should consider your clients. I am assuming web browsers are one type of client, since you mention Form Data. This is easy to create in a browser, but I don't think it's as easy to create in an Android or iOS app (I could be wrong here). If you want to target those devices also, you may want to look back in to using JSON.
Comment: Don't start implementing. Send your iOS and Android developers an example of a medium complex FORM request and see what they tell you.
Comment: Thanks! I hadn't really considered iOS and Android apps, and that FormData might not be as easy to implement there as on the web. Maybe I'll have a go at implementing methods that can handle both FormData and JSON
Comment: Unfortunately, I don't have any other developers, this is just a personal project. I'm trying to make a website with a Java backend that communicates with a REact frontend through a REST API. I don't know if this is a bit overkill, but it's just for learning purposes so it's probably best if it is.
Answer: Your question is grammatically incorrect.
I am considering that you are asking:
"Is it ok to use REST request in
'Form Data' with POST method,
when the response is in JSON"?
The answer is short: "It is absolutely OK".
To add more, you can request with any method, may the response be in any format.
(Just that, it will be dependent upon server side programming).


Long Exposure Photo vs. Video

Question: If I want to make some cool photos with long exposure times but not having a good camera that allows me to define the time, can I get the same result recording a video and make the superposition of its several frames in my computer?
Answer: Video has a much MUCH lower resolution than photos.  You can however do photo stacking and use a device called an intervalometer (assuming your camera has a remote port).

Long Exposure Photo vs. Video


German National Visa

Question: The national employment visa has "§ 2 ABS 1 BESCHV (BLAUE KARTE EU) AUFENTHALTSDAUER ENTSPRICHT GULTIGKEIT" in the remarks. Can someone help understand what this means?
Comment: I suspect that it is the name of the officer who issued the visa. If I recall correctly this is common on German visas.
Comment: *Wegener* does not seem to be a German word (although it seems to be a relatively common name).  Are you certain that you have transcribed it correctly?
Comment: It was in the next line with some indent I assumed it to be a part of that sentence.
Answer: It says tha according to §2 part 1 of Beschäftigungsverordnung (Blue Card EU) you can stay in Germany as long as your visa is valid. (As opposite to visitor's visa which often have a shorter period of stay than validity period).

German National Visa


"Re-optimize" feature in Commercial Optimization

Question: How does the "re-optimize" feature work in commercial optimization solvers such as IBM CPLEX and Gurobi? I recently experienced a considerable performance boost by re-solving a model with incremental changes to the model. I was interested to learn how those solvers improve subsequent computations.
Comment: What kind of problem are you solving? LP? MILP?
Answer: CPLEX has an advanced start parameter which dictates how it acts when solve is called on a previously solved/partially solved model.
For MIP models with the default setting of the parameter, if you partially solve a model (stopping short of proven optimality) and then tweak solver parameters (without altering the model) and solve again, CPLEX will pick up where it left off, starting from the search tree left at the end of the first run. If you change the model, I don't think the old search tree can be used, but CPLEX can try to use the previous solution as a starting solution (using heuristics to try to "repair" it if changes to the model made it infeasible). A different setting of the parameter tells CPLEX to restart from the root but try to retain the current incumbent solution if there is one. (I'm not sure if CPLEX tries to repair the solution should it no longer be feasible, or just discards it.)
For LP models with advanced start turned on, CPLEX will attempt to start from the final basis of the previous run or, if the barrier method is being used, try to restart from the last "barrier iterate".
So, assuming the model has changed, a "hot start" for an LP might allow the solver to get to a feasible basis faster (perhaps by taking the last basis of the previous run and using dual simplex to restore feasibility) or might provide a feasible incumbent / primal bound sooner (by repairing a feasible solution to the previous model). Note the use of the word "might".
Answer: Probably this link from Gurobi will help. You have to call the optimize() function in gurobi after you change parameters like the rhs of a constraint, add/remove constraints, change bounds of variables, change objective coefficients or hyperparameters like optimal gap, integrality gap (for MIP), turning certain constraints into lazy constraints (kind of delayed row generation), changing warm start etc.
Basically the solver re-solves the model and there's option to consider the last feasible candidate set.
Answer: Here are two threads published by @Erwin Kalvelagen on his blog that would be useful:

MIP Starts sometimes disappoint

Modern MIP solvers allow to use a good integer solution to "warm
start" the branch and bound process. This looks like a very good
approach to cut down on total solution times, and it sometimes is. But
in many cases it turns out, finding good solutions and passing them on
to the MIP solver is not worth the while.

Reliability of NLP solvers

NLP solvers can fail for a number of reasons. One way to increase the
reliability of a production run is to use a back-up solver in case the
main solver fails. In GAMS primal and dual information is passed
between SOLVE statements even if different solvers are used. This is
actually very useful in a case I just observed.

I was really enjoying both.


Is there an easy way to add YTD giving to receipts?

Question: We have a client that we moved from Donorperfect who brought up that they feel the receipt tools are incomplete without the ability to include YTD (year to date) giving on receipts. This seems like a simple and common request. Am I missing something simple here?
Answer: Install Jamie McClelland's Summary Fields extension - see here - and insert Total Contributions this Year as a token.
Comment: I guess I was more looking for a transaction history of giving YTD. So if they have given a monthly donation it shows them a history of those individual donations. Similar to what you might receive as a tax receipt at the end of the year only this would be cumulative on every receipt.
Answer: It sounds like you're looking for the Contributions Table Token extension: https://civicrm.org/extensions/contributions-table-token
Comment: That is perfect! Awesome.


What is Microsoft SharePoint?

Question: I have heard that Microsoft SharePoint was used by many companies. Could someone tell me briefly what is SharePoint and why is it popular?
Comment: With all the fuss about Windows and Office, I don't think Microsoft did a very good job introducing and advertising SharePoint. I've been a programmer for nearly 10 years (meaning I've been working with technology) and didn't know what SharePoint is till I saw this question! Good question really.
Comment: [Very good answer to similar question](http://stackoverflow.com/questions/5946659/what-is-sharepoint-development-from-a-developers-point-of-view/5948618#5948618)
Comment: its a collobration site. It has connection with documents like word excel. It allows you to manage users easily. It is a good tool if you use it simple. If you want to do lots of customization it brings lots of problems. I am working with sharepoint online and there are many known issues which does not have workarounds. So if you lack of time you should not use this.
Answer: What is SharePoint?
The latest version of Microsoft SharePoint software is really two different products:

Windows SharePoint Services is a free download for Windows Server. In the latest version, known as WSS v3, collaborative web sites templates include basic blog and wiki services along with list templates for Image Libraries, Document Libraries, Contact lists, Calendars, Tasks and much more.
Microsoft Office SharePoint Server 2007 or MOSS for short is built on Windows SharePoint Services. As a member of the Office Server product platform, it leverages the Microsoft Office client software to provide content on the web. Integration with Word, PowerPoint, Excel, Access and InfoPath provide rich web content from familiar content creation tools.

Why is it so popular
File Sharing
SharePoint originally became popular because it was an easy way to share documents on the web. Many organizations that adopted SharePoint in the 2003 versions capitalized on the ability to upload documents to Document Libaries and share those documents with others.
Company Extranets
One great example of this web based sharing, is a company extranet where users are not all in one location or authentication domain. Using form based authentication, accounts can be created for people across physical and company boundaries. By allowing one place for shared documents around a task rather than a corporate entity, SharePoint goes way beyond the common file share.
Content Management
There are plenty of other Content Management Systems, but MOSS incorporated the functionality of the previously name Microsoft Content Management System which itself often cost more than MOSS alone.
Search Search is greatly improved in SharePoint 2007 technologies. Search results are security trimmed, relevant and performant unlike the previous 2003 version. Bad search in SharePoint 2003 products lead to a lot of dissatisfaction with the product.
Answer:
what is sharepoint

Sharepoint is really two different technologies: Windows Sharepoint Services (WSS) and Microsoft Office Sharepoint Server (MOSS).  WSS is free and it comes with Windows Server 2003. MOSS isn't free.
WSS provides lots of out of the box functionality for managing documents and projects online.  It manages documents in "document libraries."  These are folders with permissions and different views of your documents.  Projects, tasks, issues, or any tabular data, is managed in lists.  Lists are similar to document libraries.  They have permissions and views as well.  It provides some simple search as well.
MOSS provides a better search (it's supposed to at least).  It also has more publishing capabilities (WSS doesn't).  And you have more control over page layouts.  It's meant more for internet style sites while WSS is more for intranet sites.

and why is it popular?

WSS is popular partly because its free and partly because it just does so much out of the box.  You can solve many common office requests with WSS.  Stuff like issue trackers, project management and document management are trivial in WSS.  That said, its a jack of all trades - good at many, master of none.
MOSS is probably less popular because its not free and having used it for a year, I don't see as much value in it as WSS.  Search isn't that great.  It does do a good job of creating a company directory.
Answer: I've been working with SharePoint since v.1 and I could tell you that SharePoint is a:

Document management server
Web content management server
Portal solution
Search engine
List-based repository
Collaboration site
Replacement for file shares
etc etc...

...but if I have to summarize in one sentence what SharePoint is I would say:

Sharepoint is Microsoft's Web OS.

That's real the secret of its success. Many people imagined the Web OS as something like these. A Web OS is not something that is meant to look like a desktop OS. A Web OS should be a WEB PLATFORM in which all sort of applications can be built on and users are able to collaborate with.
Think of SharePoint as the 2.0-era version of Windows :-)
Comment: 2.0-era version of Windows? But it seems so out-dated.
Comment: @sachaa , do companies still invest in SharePoint? because many of the features were taken off by O 365- SP ONline and we have very limited capabilities in SP! i think, many companies avoid SP ONline and choose .net/asp.net MVC  instead. is it true?
Answer: Previous answers describe what sharepoint is, but don't do a good job describing why it's popular.  Yes, it gives you all that neat doc-management stuff out of the box.  Yes, it integrates tightly with Office.
The OOB features are 1/10th of the whole story.  Sharepoint exposes a comprehensive .Net object model that lets you customize the thing to your hearts content.  People are coding amazing things with MOSS 2007.  With the object model, you can build and customize sites via code, in response to external events.  You can write custom "web-parts" (controls hosted on special pages) that consume both internal (sharepoint) and external data.
Check out Sharepoint Blogs to see what people are doing with it.
Answer: Very good points so far but I'll try my best to add something. :)
SharePoint is not just 2 technologies. It is a set of products and technologies brought together by Microsoft into one immense product that comes in 2 flavors. The 2 flavors are Windows SharePoint Services (WSS) and Microsoft Office SharePoint Server (MOSS). MOSS does come in standard and enterprise.
[Some of the technologies used in SharePoint: Windows Workflow Foundation, ASP.NET, Web Parts, XML (included XPath, XSLT, etc), SQL, Web Services - to name a few I can think of off the top of my head]
No matter the version you choose, SharePoint allows for web-based capabilities to allow users to create, organize, distribute, and maintain information. Because of this, the most common uses for SharePoint sites are intranets and project/team sites.
SharePoint also has incredible possibilities as an application platform. Looking at the web part and workflow pieces alone you can begin to realize the potential. For example, automation of authorization processes within an organization can quickly be developed without any code using SharePoint Designer. (FYI: more complex workflows would require Visual Studio but many simple workflows can be designed using the point and click functionality of SharePoint Designer)
While MOSS only extends upon the WSS, it does add a large amount of functionality that can be very important and useful to a business. Some of the more important features available in MOSS and not in WSS are: records management, document retention and auditing policies, browser based forms (InfoPath forms without installing InfoPath on client machine), and some of the business intelligence capabilities. Amazingly we're seeing interest in the social networking features of MOSS too. (easy to read list of features not in WSS that MOSS has)
Why is SharePoint used? I was doing some research not to long ago on this exact subject and I found a research study that cited 5 key benefits:

Ease of information access
Streamlined internal communication
Increased end-user productivity
Optimized document management practices
IT time savings

Sorry if that turned into a bit of a ramble.
Answer: It's a collaboration website.  All of the members on a team can update a single calendar and upload shared documents to a single repository.
Answer: I think in this case Wikipedia have it right

Windows SharePoint Services (WSS) is the basic part of Microsoft SharePoint, offering collaboration and document management functionality by means of web portals, by providing a centralized repository for shared documents, as well as browser-based management and administration of them. It allows creation of Document libraries, which are collections of files that can be shared for collaborative editing. SharePoint provides access control and revision control for documents in a library.

In a nutshell Sharepoint is all about corporative management and collaboration features. Your company have a Windows 2003 server? Here you go. WSS 3.0 is here up and running.
Answer: Microsoft Office Sharepoint Server (MOSS) is a combination of two previous products, Microsoft SharePoint and Microsoft Content Management System.
It has a large number of features out of the box that are very desirable for any single system, including hosting files with customisable metadata. Page and file publishing that is enabled for end users, excellent search... the list goes on.
Essentially it is designed to enhance and organisations collaboration activities across the entire enterprise, leveraging the organistations existing Office application to create an enterprise system.
Answer: SharePoint is the reason I'm considering taking advantage of a suicide booth.
In all seriousness, the rest of the answers are spot on. The differences between WSS 3.0 and MOSS 2007 commonly trip people up ("why pay for MOSS when WSS is free?" for example).  SharePoint is a very complex and rich product that is integrated into other Microsoft applications, like Project Server 2007 and Team Foundation Server.
Why should you care about it? It depends. There are quite a few opportunities out there for experienced SharePoint developers and administrators. It can very quickly become the singular focus of your career if you decide to put a lot of effort into learning it.
Answer: Sharepoint, MS OFFICE proxy circa 2003...
remember when you emailed a copy of that word doc out to the whole company, that's what sharepoint is for, but apparently you missed the introductory gotomeeting training course.

What is Microsoft SharePoint?


What's the point of removing $1$ from the list of primes and having an empty product in the fundamental theorem of arithmetic?

Question: I was reading about how we stopped considering the number $1$ as prime since this would mean the fundamental theorem of arithmetic wouldn't apply any more (since we can repeat the number $1$ over and over again and then the factorization wouldn't be unique) however, this got me wondering about the unique factorization of $1$ itself and I found out that we call it the "empty product" but what is the point of this? If the point from removing $1$ from the list of the prime numbers was to not make it an exception while stating this theorem and some others but this added another definition to make up for it so it feels like there was no point in doing it in the first place. Is there any other reason why we removed $1$ from the list of primes and made this?
Comment: The empty product is defined more generally than just for this theorem and is useful. In other words: empty products are useful and natural in general.
Comment: It seems part of your puzzlement is due to your belief that allowing $1$ as a (empty) product (of primes) is done to "make up for" excluding $1$ as a prime number. Why do you believe that (and what precisely do you mean by "make up for it")?
Comment: would you mind elaborating more please? like giving an example and such
Comment: I don't know if this will help. In any case, the empty product in a category C, when it exists, is a terminal object of that category. The positive integers are a partially ordered set via $a<b$ iff $b$ divides $a$, and thus as a category. Since $1$ divides everybody it is the terminal object of that category and thus the empty product. More generally GCDs are categorical colimits and LCMs are categorical limits.
Comment: [Related](https://math.stackexchange.com/q/47156/1508).
Comment: By the way, saying "we stopped considering the number $1$ as prime" is [slightly misleading](https://arxiv.org/abs/1209.2007).
Comment: @DanielFischer Cool paper. Thanks for linking.
Comment: thank you everyone!
Answer: There is actually a more fundamental reason why we exclude $1$. Primes are usually defined (in any integral domain $R$) as $p \in R$ such that whenever $p | ab$ then $p | a$ or $p | b$.
However, this definition always excludes units. Since units divide everything, every unit would be trivially a prime. This is because we generally want to aim for unique prime factorization. That is, for any $n \in R$ we want a unique list of distinct primes $p_1,..., p_k$ and positive integers $\alpha_1,..., \alpha_k$ such that
$$ n = \prod_{i=1}^k p_i ^{\alpha_i} $$
If $1$ was a prime, then we would have $1 = 1^2 = 1^3 = ...$ so we lose uniqueness. Unique prime factorization can be useful for many arguments and if we count primes as units we would always have infinitely many factorizations.
Answer: It is generally useful to define empty products (and sums, intersections, etc). If we have any associative and commutative binary operation on a set $S$ such that there is a neutral element with respect to this binary operation, we define the empty operation to return the neutral element. For instance:

$\sum_{x\in\emptyset}x=0$, the empty sum is $0$.
$\prod_{x\in\emptyset}x=1$, the empty product is $1$.
$\bigcup_{A\in\emptyset}A=\emptyset$, the empty union is the empty set.
$\bigotimes_{V\in\emptyset}V=\mathbb F$, the empty tensor product is the base field.

The last one may be a bit abstract, but I wanted to show that there are more than just the three "obvious" operations where we do this. The reason why we do this is that this way, if $A,B$ are disjoint subsets of $S$, then we  have the simple rule that
$$\sum_{x\in{A\cup B}}x=\sum_{x\in A}x+\sum_{x\in B}x.$$
The same goes for all other types of commutative, associative binary operations. This is important in different fields of mathematics. For instance, we need the empty tensor product to define a useful tensor algebra. So defining an empty operation is not something new, done specifically to salvage the unique prime factorization theorem (though that would be worthwile all by itself). It's just a natural definition to choose, and it's useful elsewhere as well.


How to enqueue 2 rtl css

Question: I tested my website with https://wordpress.org/plugins/rtl-tester/ plugin when wordpress language is english.It seemed good.So Do I still need to make style-rtl.css? If I need to make it, how can make and enqueue two rtl css because I have 2 theme css files? Thank you
Answer:
When using a CSS creator tool, you'll have to enqueue this
  style-rtl.css so WordPress knows when to load this version. All you
  need to do is add a snippet to the functions.php file. This allows
  WordPress to load the right stylesheet when it is set to RTL language.
  Simply add the wp_style_add_data() information to your existing
  enqueued styles function. If you are using a devoted override
  stylesheet the no special functions are needed.

you have already enqueued the style, wp_style_add_data() does not enqueue, it adds meta data to an already enqueued style and this function does not allow for empty parameters. see below.
if (is_page_template('page-templates/full-page.php')) {
      wp_enqueue_style( 'lucieaverillphotography_style', get_stylesheet_uri() );
      wp_enqueue_style( 'lucieaverillphotography-full-page', get_stylesheet_directory_uri() . '/css/full-page.css', array( 'lucieaverillphotography_style' ) );
      //wp_style_add_data( 'lucieaverillphotography-full-page' );  --> not needed & cannot be used without required inputs

}

But.....you could combine all your css into a single file and call this as default on all pages (call ie8 specific stylesheets if you want....), this way it can be browser cached and after the 1st visit, your css loads faster...Brush up on CSS specificity and ids/ classes, it will save you a lot of work in the long run!
If you want template specific changes to css you have a couple of options

if the css changes are in the article/ page, there will be usually a
  id/class set unique to that page (or add one yourself).
add custom css directly to the template (it works anywhere in the
  page, wont be popular with standards but for the moment you can put
  css rules anywhere inside style tags
Add a custom class into your header for the body tag, e.g. >

You can then specifically target css in your template... e.g.
page-id-2 header{ display: none;} //-->use chrome inspector to see what classes are outputted on each template

How to enqueue 2 rtl css


Triple stars with retrograde orbits

Question: Where can I find the observed frequency of triple star systems where the outer star is in a retrograde orbit?
Comment: Wow, I'm not aware of even one such star system, though I'm sure they exist.
Answer: The usual recipe used in the population synthesis literature is that triple stars comprise ~10% of all stellar systems and the mutual inclination is uniform in the cosine.  Most of these systems have a large enough semi-major axis ratio that the inner binary is dynamically decoupled from the outer binary, so retrograde orbits will be just as likely as prograde orbits.  So, to an order of magnitude, ~5% of stellar systems should be triples with retrograde orbits.
Things get more complicated if you are interested in more details.  More massive stars have higher multiplicities, so the fraction is probably somewhat higher for them.  For more compact systems, dynamical effects like the Kozai-Lidov mechanism will become important and can lead to prograde orbits becoming retrograde and vice versa.  Moreover, in compact systems, retrograde orbits are slightly more stable than prograde orbits, so they are likely to be a little more overrepresented, though I'm not aware of any observational evidence that there is any great difference between the two.
If you want more details on the observations of multiple stellar systems you should read Raghavan et al. (2010).  However, I don't think that they measured mutual inclinations.  In general those measurements are very difficult to do.  Andrei Tokovinin has done a lot of great observational work on triple stars as well, so you might want to look at Tokovinin (2014) and Tokovinin (2008) among other papers.  There's also a good review by Duchene & Kraus (2013).
Answer: I would say that this sort of system would be near impossible. Both the mechanics of triple star systems being very complicated and the fact that have the outermost star would have to be captured, not from the original local stellar material, no easy feat.
Basically, the system would be virtually non existent, especially in the long term due to large gravitational wave energy decay (thanks LIGO) and general instability.

Triple stars with retrograde orbits


Invalid geometry - lines

Question: In QGIS I'm attempting to create a buffer zone around a number of connected lines, then use the buffer layer to clip another layer. The lines features were provided as a shape file, and buffering works fine. However when I try to clip with the buffered layer I get an error stating 'invalid geometry'. Upon closer inspection, there is a line not connected to the others (see image), which appears to be the source of the error. How do I connect this line to the other? I've experimented with edit features (extend, reshape etc.) but can't seem to find the function I require to link them.
Comment: This is not an invalid geometry. Invalid geometries are e.g. self intersecting geometries, or duplicate nodes.
Comment: When I dissolve buffer the lines into a new layer, then try to clip another layer with this buffered layer I get this message: Feature (36) has invalid geometry. Please fix the geometry or change the Processing setting to the "Ignore invalid input features" option.
Execution failed after 0.06 seconds
Comment: Use Fix Geometries tool to fix them
Answer: Use Fix geometries to fix them:

Attempts to create a valid representation of a given invalid geometry
without losing any of the input vertices. Already valid geometries are
returned without further intervention. Always outputs multi-geometry
layer.

Invalid geometry - lines


CiviEvent rejects all online registrants for a free event

Question: I have set up a free event (type "webinar") with online registration, but Civi automatically rejects anyone registering for the event. It is not related to waitlisting because the behaviour continues when I disable the relevant status categories. Can anyone help?
Answer: Welcome to CiviCRM SE. Could you please provide some more details about 'rejects anyone registering for the event'?
If users are getting errors on the screen please can you add the error message to your question?
Check in CiviCRM config log to find if any error was recorded during user registration.
Check if the problem is specific to a single event or any event.
In case your system has a module/extension/plugin related to the Event, turn it off and check if the problem resolves.
If you have Civi-rules for Event, turn it off and check if the problem resolves.
HTH
Pradeep
Comment: Thank you! Users receive an on-screen confirmation of registration, but then receive an automatic email,
"Dear XXX
I am sorry to tell you that your registration for this event has been rejected. This is because you were not originally invited to this event.
Kind regards,"
The participant is recorded as "Rejected" and this cannot be changed without changing the participant type to "Invitee" and then changing the participant status manually. I will try those tips for checking what might be driving the behaviour.
Comment: I believe this is not Civi default behaviour, do you have any Civi rules set up for such condition and sending email?
Comment: Solved! I found a CiviRule over-riding participant status, which has been corrected.
Comment: Excellent!!! Could you mark the answer as resolved?


Can data be forensically retrieved off an encrypted hard drive?

Question: If a hard drive is encrypted, is it still possible to retrieve data off of it? What about if the password to decrypt it is known? If this is the case, given that OSX now encrypts your drive by default, does that mean every mac in the world, has data that cannot be retrieved after deletion?
Comment: possible duplicate of [Is it possible to recover securely deleted data from H.D.D using the forensics?](http://security.stackexchange.com/questions/53253/is-it-possible-to-recover-securely-deleted-data-from-h-d-d-using-the-forensics)
Comment: @raz: I'm not convinced this is a duplicated, since here the data is not securely deleted. The question here seems merely to actually know if it remains useful to delete securely files in an encrypted partition.
Comment: @WhiteWinterWolf The OP states that "it may be possible to retrieve data off a harddrive even when they've been **wiped several times**".  This would imply some attempt at [secure deletion](https://security.stackexchange.com/questions/10464/why-is-writing-zeros-or-random-data-over-a-hard-drive-multiple-times-better-th). I could be wrong, maybe the OP can clarify.
Comment: @raz: I think this is just an intro to highlight the fact that, in general, "deleted" files may still remain retrievable. Only then the OP begins with his actual question. I admit that such intro also has the side effect to mislead the reader... I actually think it could even be safely deleted.
Comment: @Olppa: Since you do not mention disk wiping neither in the title nor in the actual question (you only mention disk encryption), I assumed as stated in my comment above it was some kind of intro. If I'm wrong and you actually meant if it was possible to retrieved data from an encrypted disk wiped several times, feel free to undo my edit by clicking on the "edited ... ago" link you will find below your post then selecting "Rollback".
Answer: All current disk encryption methods strength relies on the key secrecy.

While your key remains a secret (and it needs to be strong enough to remain one), then the content of your disk at rest remains a secret. I say "disk at rest" because when the computer is running, ie. you already unlocked the drive yourself, then your file-system is accessible and also the secret key could be retrieved from your computer RAM.
When, since you mentioned this situation in your question, the key is known by the attacker, then the disk encryption does not bring any value anymore. If your file-system keeps the data of deleted files on the disk, then this data will still be recoverable.
The encryption mechanism and the file-system are two different layers, the encryption goal is to protect unauthorized access attempts to the file-system, but once this obstacle is removed then the file-system becomes freely accessible and keeps the same properties as in unencrypted disks (there might possibly be however some subtleties coming with the abstraction brought by this supplementary encryption layer and making data retrieval more difficult, but I would not rely on such side-effect to bring any real security).

So, if the question here is "Should I wipe highly sensitive files in case I am forced to reveal my encryption key", the answer is that this makes sense. Apart from such case, secure file deletion will not bring any value against attacker ignoring your secret key.
Comment: Can you please clarify what you mean by " Apart from such case, secure file deletion will not bring any value against attacker ignoring your secret key."?
Answer: Macs use FileVault to encrypt your data. It's been available on prior OS X versions, but I believe now with Yosemite, it's encouraged to use it and much easier for the standard user to toggle it. This encrypts your hard drive.
Technically, it would still be possible for someone to retrieve the data from an encrypted drive. To crack AES, you would need a lot of money and a very powerful machine. The likelihood of someone getting your data would be extremely low. Someone with lots and lots of time, money, and resources (government)....maybe?
Answer: It is doable to crack 1024-bit RSA keys but it takes many years as you can test here; so that is why Apple defies FBI and offers encryption by default on new operating system . So if you have precious information to hide, there is a way, for a skilled and well equipped team, to take advantage of data remanence using cold boot attack if you choose to leave your laptop in a sleep state instead of powering it down.
Conclusion: for at least twenty years up, encrypt your disks and do not worry that much.
Answer: Any data that is encrypted with publicly available encryption can be decrypted... otherwise I can assure you that it such encryption algo's would not be available to the public. For the "every day user" there are no options for encryption that are not able to be broken. Our government would not and does not allow it.
"Deleting" data from a hard drive is an essentially meaningless term. It just "frees up" that particular block/segment of memory space for future data... now this is a general rule and there may be particular implementations which remove or attempt to remove any data that is on the drive at that time but in the 'typical' use of the word "deleting" then, no, it does not actually 'remove' the data itself... again, just frees up that memory address to hold other data.
Quick and short answer to your question:  Yes, the data can be retrieved in almost all but the most extreme cases. But the issue is at what level of computational time and space is required to do so...
Comment: Can you explain how can decrypt encrypted data when *"publicly available encryption"* is used without knowing the encryption key?
Comment: I was addressing the question as asked: "... if the password to encrypt it is known..." so that is the context of my reply.
Comment: you may want to clarify your answer then, you don't make reference to "if the user has the password" and it could make people think that you were saying that it was possible to break the encryption itself, instead of just decrypting it using the correct key.


how to pip install 64 bit packages while having both 64 bit and 32 bit versions?

Question: I have decided to learn generic algorithms recently and I needed to install Tensorflow package. Tensorflow run on python 64 bit only, so i install python 3.5.0 64 bit without uninstalling python 32 bit. because i was afraid to lose my packages on python 32 bit by uninstalling it. The problem is how can i force pip install to install a package on my python 64 bit version instead of 32 bit version.
Comment: it's windows 10
Comment: but i have both of them now. i have 2 options editing IDLE on 32bit and 64 bit
Comment: yes both of them run properly but 64 bit does not have the packages i had installed on 32 bit already
Comment: That's fine, just checking, try the method in Ashish's answer, it will work if it's installed properly
Comment: my previous 32 bit was installed on C:\Python and my newly installed 64 bit python is installed on C:\Users\office\AppData\Local\Programs\Python\Python35 .I'm not sure if python has decided to change the default install rout to this path nowadays or python had detected i had 32 bit version already and choose a new path to install
Answer: If you have actually managed to install both x64 & x32 packages, you could simply do
C:\path\to\corresponding\python.exe -m pip install <package>

This will ensure you use the correct pip and install the package for the specific python instance.
Comment: On command Prompt i cd to the corresponding folder(pathon 64 bit) and then pip install the package. unfortunately it didn't work
Comment: @MohsenHaddadi The `-m` stands for *module*. And yes, uninstalling python itself will surely remove all the packages too. If you want to reinstall all packages, just make a note of all the packages by doing `pip freeze > \path\to\backup\requirements.txt`. So, if you want to reinstall later, you can just do `pip install -r requirements.txt`.
Comment: You can check which `pip` version you used by checking `pip -V`. And like I have mentioned, just use the correct `python.exe` instead of trying to use the correct pip.
Comment: Wow it's working. Tyvm!!i had to upgrade my 64bit pip at first to install my desire package
Comment: by the way what does that -m mean? and do you know if i uninstall python 32 bit and reinstall it later, the packages will be deleted too?
Comment: -m mean -module, yes it will
Comment: @MohsenHaddadi You probably typed `python.exe`, which probably ran the .exe from the wrong path.  Type `./python.exe` so the executable is run from the current path.
Answer: Starting with Python 3.3, coexistence is made much easier with the Python Launcher for Windows. (Also see PEP 397.) From the command line you can use "py" or "pyw" in place of "python" or "pythonw". The py command allows you to specify the revision and version of python to run.  For example, open a command window and type in "py -3". This runs the latest revision of python 3 available and defaults to the 64 bit version if it is available. On the original poster's system, entering this command will start the python 3.5-64 bit interpreter.
This command can also be used to run the correct version of pip without knowing the exact path to the python version you want to install to. "py -3.5 -m pip install [package]" will install [package] to the 64 bit version of python3.5.
If you have both the 64 and 32 bit versions installed and ever need to install to the 32 bit version, you have to enter both the major and minor revision numbers as part of the command and add '-32' to the command argument. "py -3.5-32 -m pip install [package]" will install to the 32 bit version.
Answer: If you do have both the 64 and 32 bit versions installed and need to install a 32 bit version package only, you have to enter the target -t (32 bit Lib) with pip3, e.g. install bitcoin lib:
 pip3 install -t C:\Users\
       max\AppData\Local\Programs\Python\Python36-32\Lib bitcoin

Answer: I have both 64 and 32 bit python environments on my machine.
To build targeting 32 bit or 64 bit, i edit the environment variables setting the PATH for the whole python installation and  one environment variable pointing to the scripts area, where pyinstaller is.
.....\Continuum\anaconda3_32bit
.....\Continuum\anaconda3_32bit\Scripts
 or
.....\Continuum\anaconda3
.....\Continuum\anaconda3\Scripts

The I run pip install pyinstaller (which uses the PATH to find the required versions of PIP and pyinstaller).
The app must have been built using the correct python environment as well.
Answer: As an additional solution it's good to know that windows (or any) operating system looks for apps firstly in current directory then check path environment variable. So it's a good idea to place preferred python version's path to first position in path env variable.
Or simply replace the old pythons's path with new one.
Answer: There's nothing much you can do. I also had this issue. The best thing to do is to change your python path and install the packages on the 64 bits python.
Comment: Instead of changing python path, the easier way is to open command prompt on 64 bits python.exe directory and then type and run 'python pip install ...'
Comment: That won't work. You would be doing that foer only the current pip version (either the 32 bits or 64 bits). The only way I know us just as I said
Comment: Are you sure you have type and run 'python.exe pip install ...' after typing and running 'cd c:\ desire python version directory' on windows command prompt?


What justifies a full page modal navigation?

Question: What arguments support having a full page modal acting as a hub that takes you to different actions / pages that are linked together?
For instance imagine an app where you manage recipes, you would have a button opening a modal menu with:

View list of recipes
Add a new recipe
View list of ingredients
Add an ingredient
Manage food orders
Create a new food order
Manage food preferences

This is completely fake.
My client tends to want modals everywhere. I get the feeling this initial button should rather lead to a "space" on the website about all the above, with a vertical menu giving you access to all these things.
I'm struggling to find arguments one way or the other. Any thoughts?
Answer: Modals are used to force attention and focus the user on a single task. I have not seen full-page modals used for website navigation because the user often needs to know where they are in addition to where they want to go.
In high-stakes applications where lives or health might be threatened by mistakes from lack of attention (think car touchscreens), a full-screen nav that minimizes distractions is a good idea. But if I'm making brownies and my hands are covered in flour and I need to know what to do next and I'm going to add an ingredient and... the nav interrupts me? I'd test that with some real-time users.
Comment: This comes from the first usability heuristic, "Visibility of System Status" - let the user know what's happening. Here's an article on good nav design that talks about the importance of "you-are-here" navigation: https://www.justinmind.com/blog/navigation-design-almost-everything-you-need-to-know/
Comment: You make some very good points. Can you think of any study or research that shows that "the user often needs to know where they are in addition to where they want to go" ?
Comment: great, thanks a lot


How to say 'I miss you' in Latin

Question: How can I say "I miss you" in the sense that one misses someone and desires to be again with this someone nonetheless it is alive or death?
My dicctionary only list: miror, which is more like being surprised or amazed.
Answer: There are several ways to say this; what to say exactly depends on context and to a certain extent your mood... They all tend to revolve around the word desiderare or desiderium.
The simplest way would be to say: te desidero.
Desiderare is said of the living, not least lovers (e.g. me ames, me desideres), and the dead (e.g. after a battle), and of inanimate things (e.g. gloriam). It is only said of people or things that aren't present, but it has a strong sense of longing or (surprise!) desire.
Still it may feel a little anodyne depending on the circumstances, and if that should be the case, you can go further and say, for example, (summo) desiderio tui flagro (or teneor). That's going pretty far, of course.
Cupere is another possibility. Cupio the videre for example -- but that's not something you write to your tax consultant to make an appointment.
Answer: There's not one word that expresses this as definitively as English's modern usage, so you have a variety of options, including those that Sebastian listed, and especially if you add something like reditus to it.
I'll also add careo to the mix. It's more typical meaning is "to lack something [that you want to have]," which covers the absence part of "to miss." From L&S:

With the access. idea of the subjective state of mind or feeling, to feel the want of a thing, to miss: triste enim est nomen ipsum carendi, quia subicitur haec vis; habuit, non habet; "desiderat, requirit, indiget," Cic. Tusc. 1, 36, 87; cf. "the context: carere igitur hoc significat, egere eo quod habere velis," id. ib. § "88: non caret is qui non desiderat," id. Sen. 14, 47.

I especially like Cicero's simple definiton of carere: habuit, non habet; desiderat, requirit, indiget.
In fact, Cicero has a mixture of carere and desiderare in the same passage:

non mehercule aequo animo te careo; te autem quid mirum, qui Dionysium tanto opere desiderem?
Comment: extrañar?, extraneo?

How to say 'I miss you' in Latin


How can I add the noise to the pores in this texture?

Question: I have this texture that im trying to add pores to, Im using a voronoi texture to make the pores but they look too smooth, how would I go about mixing the noise into the pores so it blends better? Or perhaps theres a different method for adding pores like this? Thanks in advance!
Answer: The solution was easier than I thought. Just another math node adding the voronoi and the noise together does the trick. I've also added another multiply node for more control over the voronoi.