How to create wordpress plugin support page?

Question: I want to add a support page to my plugin wordpress. My plugin is already developed. Now I want to allow users to contact me for any question. I want the support button to be next to the activate and Update buttons in the plugin add page.
Comment: Downvoted *I want to add a support page*. We all want certain things, but without putting in some effort, one will ever have what they want. What have you done to solve this issue, where is your research effort, where have you failed. No one is here to do your project for you
Answer: You can use the plugin_action_links_ filter for that task:
add_filter( 'plugin_action_links_' . plugin_basename(__FILE__), 'add_support_link_wpse_220726' );

function add_support_link_wpse_220726( $links ) {
   $links[] = 'Support';
   return $links;
}

Note that you must also pass the plugin name (plugin_basename(__FILE__)) for it to work. That's why take into consideration from where you will call it.
Answer: Something like this will do it...
add_filter('plugin_action_links', 'mycustom_plugin_action_links', 10, 2);
function mycustom_plugin_action_links($links, $file) {
    $thisplugin = plugin_basename(__FILE__);
    if ($file == $thisplugin) {
        $supportlink = "Support";
        array_unshift($links, $supportlink);
    }
    return $links;
}

Sounds like you might be needing add_menu_page also, so my answer assumes your link is to an admin page.
Comment: yeh, the question sucks and confusing
Comment: Doesn't have to be, there is no real reason the plugin links point only into the site, and not out of it. It is just a lousy place for that in terms of UX, but it is possible.
Comment: I know this, but maybe you can reread first sentence of the question again, I was trying to answer the question asked.


Where can I buy a 'Conjure Flame Atronach' spell?

Question: I'm trying to play as a Mage but some units are immune to magic. Where can I buy a 'Conjure Flame Atronach' tome?
Comment: It ended up that I found it doing the Azura's Star mission.
Answer: You can purchase the spell from any of the court wizards in the Jarls' castles in the major cities once your Conjuration skill is high enough (25).
Comment: I was able to purchase it from the resident wizard in Dragonsreach, Farengar Secret-Fire, in Whiterun.
Answer: I strongly suggest, that you join the Mightyy.. College of WinterHold.
Travel to Winterhold by carriage.., Go to the bridge, and talk to the woman, she will give you the Flame of Atronach, Magelight, or Fire BOLT spell, at a mere 30 Gold! Once your in you can learn any spell you please, and do exciting quests.
Answer: You can purchase it from:

Calcelmo (at Understone Keep, Markarth)
Falion (resident wizard of Morthal)
Farengar Secret-Fire (court wizard at Whiterun)
Madena (court wizard at Dawnstar)
Nelacar (living in the Frozen Hearth inn at Winterhold)
Phinis Gestor (a mage at College of Winterhold)
Sybille Stentor (court wizard at Solitude)
Wuunferth the Unliving (court wizard at Windhelm)
Wylandriah (court wizard at Riften)

You can also create the "Conjure Flame Atronach" tome at the Atronach Forge (The Midden, College of Winterhold).
Source: UESP wiki's "Conjure Flame Atronach" article


Seeing which ports can be used for bittorrent

Question: I am connected to the Internet through a router that I forgot the password to. So I can't open up ports like usual. How can I scan for open ports that I can use for bittorrent? I would like to use a program in the Linux terminal to scan for usable ports. Can I use a well-known port?
Comment: If UPNP is enabled in the OS, Router and the bittorrent client, the ports will be opened and configured automatically in the router when the client is started..
Answer: Chances are all your ports are open going out, but that is not the information you need, and you cannot get that internally. You need an external port scan (Google port scan).
One that I always have used is "Shields up"
http://www.grc.com/x/ne.dll?rh1dkyd2 (click proceed, then click "User Specified Custom Port Probe" and read the directions)
You can also go here:
http://www.t1shopper.com/tools/port-scan/ (enter ports 1025-65535 and click scan)
In the long run, you might just be better off setting the router back to factory defaults and putting in a password you remember.
Answer: Also bear in mind that even if there are Static NATS in place each NAT has to assign a static external port and a static internal IP, so even if you find an open port there's no guarantee that it forwards to your computer anymore unless it's kept it's IP address since you last used bittorrent.


What's the difference between 'fallacy' and 'misnomer'?

Question: In which contexts the usage vary?
Answer: Though they both imply there is some kind of mistake, they are pretty different kinds of mistakes.

a fallacy is an error in inference. You have some facts and do some reasoning but come to a faulty (or unsubstantiated) conclusion. Then you've committed a 'fallacy'. Coming to a wrong conclusion is a fallacy.
a misnomer is simply a wrong name for something, in the sense that the given accepted name is at odds with the nature of the things itself. A 6'7" basketball player named 'Shorty' has a misnomer (the name 'Shorty' is a misnomer).
Answer: A fallacy is a common misconception. A logical fallacy is one type of example.
Misnomer refers, more specifically, to a wrong name or inappropriate designation -- for instance, calling Native Americans "Indians."
An easy way to remember the difference is to remember that misnomer is derived from the the Latin word for "name," nominare.
Comment: ...Or calling them Native Americans. :) Some would point out that thee folks were here before the European explorers got around to renting boats. The term I've heard recently that I liked was "First Nations".
Answer: I think Wikipedia has one of the better succinct definitions: "...a fallacy is incorrect reasoning in argumentation resulting in a misconception."  It should be noted that there are a number of distinct logical fallacies, and that an entire section of philosophy is devoted to them.  The referenced link is a good start for exploring the various flavors of fallacies.
@Mitch's answer to a misnomer is well stated.
Answer: A fallacy has a technical and a common usage, but both could be loosely summarized as "an error in reasoning" or a "logical fault".
Poor reasoning can also be called fallacious reasoning.
"Begging the question" is an example of a fallacy.
From nobelief's fallacy list:

begging the question (or assuming the answer): (e.g., We must encourage our youth to worship God to instill moral behavior.) But does religion and worship actually produce moral behavior?

Here's an example usage from a comment on Serendipity: Or, What has Software Engineering got to do with Climate Change?

I only bother to bring it up because, IMHO, an appreciation of this fallacy is necessary to appreciate the real differences between technical software validation and its verification.

Something being a 'fallacy' tends to indicate an error of process.
A misnomer is simply misnaming something, or calling something by the wrong name or a misleading name.
This can be minute and technical or broad and ideological or philosophical:

Calling that little hill Mount Brawn is an egregious misnomer.
Calling that a budget plan is a misnomer -- there's no plan, it's just budget fraud.

It is incorrect to use misnomer to mean an incorrect assumption, poor reasoning, or more general kind of error where another word should be used instead:
Don't use it this way, please:

It's a misnomer that all dogs bark.

Ugh. From the another comment found in the wilds of the Internet:
Again, please, no:

There's still a misnomer that single women pushing thirty are fatally flawed or intimidating[...]


How to stop cat from pooping on carpet?

Question: We have owned a cat for about 9 years, who has always used his litter box. We recently had a bunny for a short time and when we let it out, the bunny pooped in our living room in some of the corners. The bunny is no longer here but now the cat keeps pooping in the same spot the bunny did. How can we stop the cat from pooping in this same spot?
Comment: remove carpet maybe.
Answer: When a cat breaks litter box protocol -- unless it was unable to get to the box, e.g. by a door being closed or another cat deciding to guard it -- this is usually an indication of illness and time for a vet visit.
After that, treat the marked area with an enzyme-based cleaner (available from pet stores under multiple brand names) to remove all traces of the scent, which might otherwise encourage a repetition.
Answer: Another reason for such a behaviour might be stress. Maybe something changed? Other animals / people which trouble your cat? And please consider that cats have other standards than humans have so it might be something simple like this: I know a cat which was avoiding its litter box after a balloon burst near it.
If your cat does not have a health problem and you cannot find another reason - maybe you could to train her. E. g. put a litter box at the place your cat is using now and pull it back to the original place step by step - a short distance each day.
Answer:
We recently had a bunny for a short time and when we let it out, the
  bunny pooped in our living room in some of the corners. The bunny is
  no longer here but now the cat keeps pooping in the same spot the
  bunny did.

Cats are very much into smells, and are known to urinate or poop on places that smell like urine\poop from before.
I'm thinking your cat is pooping on those places because it can still smell that there has been poop there before.
I would've tried spraying anti-cat fumes on those places.
Several fumes/smells can be used to make a cat stay away from certain spots. Most cats hate citrus fruits, pepper, typical human perfumes, tooth paste, and certain products that can be bought in pet stores for this purpose (I don't remember what they are called).

How to stop cat from pooping on carpet?


Google Play - How to prevent downloading the large APK Expansion File when the user installs the APP from the market

Question: many of my users have problems to install my App from the Play Store due to a lack of enought internal memory. The size of the App is: APK 37MB + EXPANSION 1,3 GB.
I was aware that many users don't want to have such big data in the system memory and implemented the licencing- and download-libary example, and changed the code that the expansion-file will be downloaded directliy to the physical sd-card. But the user can run my download-process only from the options-menu within the App.
.
The problem:
Google stated here:

"...If Google Play is unable to download the expansion files, it downloads the APK only."

But this seems to be wrong. Many user complain about installation issues and "pending/hanging" downloads. They say that when they install the App from the market that Google Play tries to download the  OBB-Expansion File in the first place and (what makes it even worse) to the internal memory.
So the user can not start the App and make use of my download implementation.
As I want to make use of the security features of google's licensing mechanisms I had following idea:

Upload my app to the developer console without the expansion.
Upload another dummy-apk with the 1,3GB expansion, and don't publish it
Try to download the Expansion from the options-menu from my original app und use the licence-key from the dummy apk.

Can somebody confirm that this could work?
Is there an way to make Google Play download the large expansion directly to the external memory? Maybe if i modify the Manifest with:
android:installLocation="auto"

Any Ideas are appreciated!
Answer: Why don't you put the preferExternal value for installLocation in your manifest? This will put all files in external storage if available. Do this for all your apk files.
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
android:installLocation="preferExternal"
... >

from: app install location


Probablistic counterpart for kNN

Question: We know that the Gaussian Mixture Model is a probabilistic counterpart of k-means algorithm. Is there a probabilistic counterpart for kNN? (which is similar to k-means, but supervised.)
Comment: Parzen window based classifiers are probably what you're looking for.
Comment: Instead of the kNN predicting a class you want it to predict an array of probabilities for each class?
Comment: It sounds like "parametric" or "model-based" would be more helpful terms.
Comment: @AndrewCassidy: That is one possible generalization. The other option would be an array of probabilities over k.
Answer: The way I'd model it (I haven't seen this in the literature, but it wouldn't surprise me if it were already out there) is:
I'd think of it as expressing the posterior distribution over class labels,
given that you have a (test) sample $x$, as a marginalization over a sub-set of the training sample nodes, $n_i$:
$$
p(c \vert x) = \sum p(c \vert n_i ) p(n_i \vert x)
$$
In the back of my mind, I have the idea that the test sample is assigned-to (or is essentially the same as) one of the test-samples; but since we don't know which one, we marginalize over all of the feasible ones.
The first factor defines, for each training-sample node, the probability
distribution over class labels, given that the test-sample was "assigned"
to node $n_i$.  If each training sample has a particular label, then this might be just an indicator function for that label; the various extensions to actual distributions are going to be problem domain specific.
The second factor is the probability that node $n_i$ is the correct assignment choice.  The direct mapping of $kNN$ is to have $p(n_i \vert x) = 1/k$ when $n_i$ is in the set of $kNN$'s, and zero otherwise; i.e. a cookie-cutter type of distribution.  Again, this could be generalized into something with a softer roll-off, e.g. a Gaussian type of shape in feature space, if desired.
In my opinion, this captures the the essential general structure of $kNN$:

You pick a population who gets to  vote, this is achieved by $p(n_i \vert x)$, and then
you combine the results of each vote, in this case each vote is a probability distribution over classes, $p(c \vert n_i)$

whether you want to have a soft or hard inclusion function, the exact methods for defining the vote probabilities distributions and so on are problem-specific details.
Answer: Something very similar is Logistic regression with a Radial Basis Function (sometimes called Gaussian) kernel (http://en.wikipedia.org/wiki/Radial_basis_function_kernel), with all weights constrained to be $1$.
A fitted RBF kernel regression will compute weighted distances to various points, compute a Gaussian pseudo-probability of being a neighbor based on the distance, and average the values at the points in the training set weighted by that Gaussian pseudo-probability.
This is very similar to kNN, where $k$=size of the training set.
You can reduce the number of points under consideration via a Laplacian prior ($L_1$ regularization), but this won't have the same effect as varying $k$ in kNN, as the $k$ points chosen will be the only ones considered.
If weights are fixed at $1$, only the distance matters.  When weights are allowed to vary, it affects how much each point is allowed to vary.
Answer: This paper formulates explicitly a probabilistic version of KNN:
C.C. Holmes, N.M. Adams: A probabilistic nearest neighbour method for statistical pattern recognition. J. Roy. Statist. Soc. Ser. B, 64 (2) (2002), pp. 295–306.
Dave's idea also comes up in this paper:
A. Kaban. A probabilistic neighborhood translation approach for non-standard text categorization. Proc. Discovery Science (DS08), 2008.
Comment: Beware that in the Holmes and Adams paper the model specification is incoherent. Check out Cucala, Marin, Robert and Titterington (2009).
Answer: Gaussian mixture model is rather a generalization of $k$-means where variances are not identity matrices.  One way to construct a probabilistic model which will be a generalization of kNN is to assume there is a gaussian centered at each data point with unknown variances whose distribution is fixed.

Probablistic counterpart for kNN


Could the conference presentation be a part of my abstract?

Question: I wrote the abstract according to my thesis but realized that it's too much for a conference presentation. Could I use a part of the abstract to present?
Comment: I mean, emmm, I wrote an abstract according to my whole thesis. However, when I was preparing my presentation, I realized it was too much for a 15 minitues' presentation. I am wondering if I could use part of the data to present, in other words, some information in abstract will be neglected while some will be stressed. Does it work?
Answer: I am not quite sure I understand your question ... of course you can present your PhD(?) thesis at a conference and you are also allowed to shorten the abstract in order to fit the conference requirements.
But in general I would rather recommend to re-write the abstract completely because shortened texts tend to be sub-optimal and you might also run into the issue of self-plagiarism if you take (parts of) your abstract with copy&paste.
If by "Could I use a part of the abstract to present" you mean if you could use a part of your ideas/results etc to present then the answer is also yes. There is no rule that you have to present your whole work at once - often it is even better to present one (shorter) clear message at a conference than trying to get the whole thesis into a presentation.
---- EDIT ----
After clarification of the question ("Does it matter if the content of my conference presentation does not (fully) match the abstract that I have submitted?"):
No, it does not matter. Most people will not even realise it. If you like you can say a sentence or two in the beginning that you will focus on a specific sub-part of your abstract (and you are happy to discuss the other aspects during the coffee break etc). But it is up to you!
Comment: Thank you for your answer. I have already submitted my abstract and it has been accepted. I don't think I can make any changes to my abstract at the moment. However, I'm wondering whether my presentation will be questioned if I don't present all information in the abstract. It seems that the presentation does not correspond with the abstract.
Comment: In my experience, no one cares if your abstract and presentation do not match entirely.

Could the conference presentation be a part of my abstract？


Apache: configure prefork in a per-virtualhost way

Question: I host different sites on the same Linux server (an AWS EC2 instance), I would like to give these sites different limits via a virtualhost specific configuration. Is this possible?
Comment: I doubt it.  I suspect you'd have to have multiple versions of httpd, running on different ports.
Answer: No. If you consult the documentation for the prefork MPM (2.4 docs here), you will see that the "context" of all configuration directives have a scope of "server config". This means that they cannot be defined at a VirtualHost level.
MPMs are not the best place to try and implement resource constraints for anything other than the main process itself. You should probably look into modules that are specialized toward throttling virtual hosts.
Answer: mpm-itk has a MaxClientsVHost directive, but like the documentation (and Andrew B) says, there's probably better ways of doing what you want, like mod_qos.


All logins used on an instance is 'SA'

Question: I found out that on an instance of a certain SQL server at my company- sa is virtually the only login used by all the sessions. The SPID# extends to 130. What do you think is the impact of this? Is there any downside despite of course security? Appreciate you pitching in on this. Thanks.
Comment: Do you need a downside other than security? You have ~130 sessions, all with full and complete control over your entire instance and potentially the machine as well.
Comment: Security is the most important and biggest downside you face with that. It's best SQL practice to grant the least amount of permissions to any app, so long as the app can function. Would you give your entire neighborhood the keys to your house?
Answer: The impact is a very severe security risk. It might be that your application is hard-coded to use 'sa'; often very poorly written and implemented 3rd party apps do this kind of awful thing.
The question you need to ask is, "what can I do to fix this?", because it definitely needs fixing urgently.
If it is a 3rd party app, you may need to escalate to your support provider.
Ideally you will create a new database role, assign minimum required permissions to that role [e.g. exec on certain Stored Procedures] , then create logins/groups for your users, add them to this role, and modify the application's connection settings to use their own logins instead of sa.
You should also then create a new sysadmin login NOT called 'sa', for your own use, and then if possible, remove sa itself from the sysadmin fixed server role, and/or disable it.
Having all your users connect using a sysadmin-privileged login (even if it is one other than sa), is, to put it mildly, far from ideal.
Comment: If the application is hard-coded to use sa, you might be able to rename the sa account to something else, then create a non-privileged account named sa and test what permissions are actually necessary.  Even if you end up giving it full db_owner access to the application backend, it would still be better than having it connecting with a sysadmin account.
Comment: Yes, hence by retaining it, but removing it from sysadmin, you can always simply temporarily re-add it to sysadmin if/when required for upgrades etc. Also you don't get the issue with job ownership you alluded to.

I'd also reset the sa password as matter of urgency either way.
Comment: Also, if you rename it, check your agent jobs and make sure that any ones owned by sa get their owner changed to your new, renamed version.  There's definitely some considerations when you rename sa on an active server.  I've also heard grumbling that upgrades sometimes fail if the sa account is renamed, disabled or doesn't have sysadmin authority.
Answer: I had a server with a similar problem. What I did was to trace the sa account, use the results to determine the permissions needed, then create a new account named SystemAdministrator with the same password and grant the permissions to the new account. Then I switched the names of the two accounts so that the SA account was a regular user account and removed SA from the sysadmin role and changed the password for SystemAdministrator. I also tracked down all of the applications configured to connect with the SA login, which can be identified using the same trace. Once these applications are located, you can add ";Application Name =app1" to the end of the connection string to separate permissions by application because it will be sent to the server as application name or program name.
Sessions with a SPID below 50 are generally sessions needed by the database engine to run the server. After switching the login names, you will see that those run under SystemAdministrator. Database owners and SQL Agent job owners automatically changed since the owner sids are saved in the system tables. Refresh any SSMS Object explorer connection before verifying.
First, create the trace by going into Profiler or Extended Events and add a column filter for SA. Under Security Audit, you will want to trace the event Audit Database Object Access Event. Run this as a server side trace and specify that the file go onto a large drive. Even though the SA login bypasses the permission check algorithm, it still saves the permissions necessary to execute the statement under a column named permissions in the trace. The following script will use the profile trace file to generate the sql commands necessary to grant permissions to the SystemAdministrator account:
<code>declare @filepath varchar(1000)

SELECT
     @filepath=cast(value as varchar(1000))
FROM sys.fn_trace_getinfo(5) -- replace this number with your traceid
where traceid=5 and property=2

-- creates the necessary users in the databases
select distinct 'create user' as permission_desc, DatabaseName, 'use [' + DatabaseName + '];
if not exists(select * from sys.database_principals where name =''SystemAdministrator'')
    CREATE USER [SystemAdministrator] FOR LOGIN [SystemAdministrator]' as SQlStatement
from (
select
    case
        when permissions =1   then 'SELECT'
        when permissions = 2  then 'UPDATE'
        when permissions = 4  then 'REFERENCES'
        when permissions = 8  then 'INSERT'
        when permissions = 16 then ' DELETE'
        when permissions = 32 then ' EXECUTE'
        when permissions = 4096  then 'SELECT ANY (at least one column)'
        when permissions = 8192  then 'UPDATE ANY'
        when permissions = 16384 then ' REFERENCES ANY'
        when permissions is null and left(cast(textdata as varchar(max)),8)='Truncate' then 'Alter Table'
    end as permission_Desc,
    *
from fn_trace_gettable ( @filepath , 1 )
where DatabaseID<>32767 and XactSequence<>0 and DatabaseName not in ('master','tempdb','model','msdb') and permissions =1
) data1

-- grant granular permissions to SystemAdministrator

select distinct permission_desc,  ObjectName,   DatabaseName, OwnerName,'use [' + DatabaseName  + '];grant ' +  permission_desc collate database_default + N' on [' +
    DatabaseName  + N'].['  +   OwnerName  + N'].[' +   ObjectName +N'] to [SystemAdministrator]'  SQLStatement
from (
select
    case
        when permissions =1   then 'SELECT'
        when permissions = 2  then 'UPDATE'
        when permissions = 4  then 'REFERENCES'
        when permissions = 8  then 'INSERT'
        when permissions = 16 then ' DELETE'
        when permissions = 32 then ' EXECUTE'
        when permissions = 4096  then 'SELECT ANY (at least one column)'
        when permissions = 8192  then 'UPDATE ANY'
        when permissions = 16384 then ' REFERENCES ANY'
        when permissions is null and left(cast(textdata as varchar(max)),8)='Truncate' then 'Alter Table'
    end as permission_Desc,
    *
from fn_trace_gettable ( @filepath , 1 )
where DatabaseID<>32767 and XactSequence<>0 and DatabaseName not in ('master','tempdb','model','msdb') and (permissions <>1 or (permissions is null and left(cast(textdata as varchar(max)),8)='Truncate' ))
) data1
</code>

All logins used on an instance is 'SA'


Why is a conservative force defined as the negative gradient of a potential?

Question: I'm learning about work in my dynamics class right now. We have defined the work on a particle due to the force field from point A to point B as the curve Integral over the force field from point A to B. From math I know that if a vector field has a potential, we only need to evaluate the potential at point B minus the potential at point A to get the result of the curve Integral. In the text that I'm reading, it's explained that if the integral over a force-field is path-independent, then the force field $F = -{\rm grad}(V)$, where $V$ is the potential. Why is it defined as the negative gradient? Doesn't one determine the potential from $F$ mathematically. Why do we impose the sign on the potential?
Answer: We introduce a minus sign to equate the mathematical concept of a potential with the physical concept of potential energy.
Take the gravitational field, for example, which we approximate as being constant near the surface of Earth. The force field can then be described by $\vec{F}(x,y,z)=-mg\hat{e_z}$, taking the up/down direction to be the $z$ direction. The mathematical potential $V$ would be $V(x,y,z) = -mgz+\text{Constant}$ and would satisfy $\nabla V=\vec{F}$. This would correspond with decreasing in height increasing in potential energy which would make us have to redefine mechanical energy as $T-V$ in order to maintain conservation.
Instead of redefining mechanical energy, we introduce the minus sign $\vec{F} = -\nabla V$ which equates the physical notion of potential energy with the mathematical notion of the scalar potential.
Answer: If the resultant force acting in a body is give by minus the gradient of potencial you can show that $\frac{dE}{dt} = 0$. Where E is the total energy of particle. So total energy, kinect + potencial is conserved.
In 1-dimensional case:
$\frac{dE}{dt}=\frac{d(\frac{1}{2}mv^2+V(x))}{dt}=mv\dot{v}+\frac{dV}{dx}\frac{dx}{dt}$
$=v(ma + \frac{dV}{dx})$
Answer: Solved:
Read pages 9-10 of this document(under title Conservative forces and conservation of energy). It is defined as -$\nabla$V so that the energy is conserved. Read through the proof and towards the last step you will see that it needs to be defined that way so that mechanical energy is conserved. This worked for me and I am sure it will work for you as well.
Answer: Answer you people have given is right, but it is from mathematical background.
Physically, conservative force is a dissipative force. Due to dissipation properties we right as gradient of potential and negative sign comes from its opposite direction of action.
Comment: A conservative force is not a dissipative force.


RubyGem download number seems artificially high. Are there bots that download from RubyGems.org?

Question: I just uploaded a RubyGem two days ago. It doesn't do much, but it is a wrapper for part of the Facebook Graph API. Today, out of curiosity, I checked the gem's download number, and it was at 300 or so, which was very surprisingly high. I'm wondering if bots download from RubyGems.org, or is there actually a possibility that my gem has been downloaded 300+ times by developers?
Comment: There are at least 50 mirrors of rubygems, possibly quite a bit more.  Every version of every gem I've ever uploaded had at least 50 downloads, even though most of my gems aren't generally that useful.
Comment: This is not really a fit for Stack Overflow. Short answer though: Congratulations that the Ruby community took an interest in your gem. Keep writing gems!
Answer: Everybody know that bundle install is a bit slow. So someone can consider to keep rubygems mirror locally.
There is the gem for this task: https://github.com/rubygems/rubygems-mirror
So that's why download number is high.
Answer: I'm certain bots influence the count. I released several updates and version bumps to a gem I wrote over the course of a day or so. Then the highest release remained unchanged for months. The gem hasn't really caught on. If I look at the download stats, the totals for the releases that were only the latest release for a few hours have similar totals (and download patterns) to the version of the gem that has been the latest version for months and months.
That said, my totals peaked at around 30, so maybe there are some real users in there. If you want to know for sure, make a quick improvement and bump the version and compare the usage trends.
Comment: same measure for my little gem (ruiby) : 30 downloads at each update, and no user (a big bug with linux was not signaled...)


What does the intonation pattern on "online" mean or imply?

Question: What does the speaker mean or imply with the intonation on "online" at 0:31 around? A negative and doubtful query? Does the intonation pattern on "online" completely fall at the end? Or, does it slightly rise at the end because it occurs before a pause - intonation unit?
Comment: The speaker is expressing mockery or disbelief – a murder mystery online isn't of any interest to him. There is a slight interrogative lilt, but it isn't really a question. If any, "a murder mystery, online?" implies "Did I hear you right?"
Comment: Very relevant: https://english.meta.stackexchange.com/questions/13375/why-cant-we-add-video-or-even-audio-clips-to-posts
Answer: As pointed out in the comments, the speaker's tone, at least to me, seems to express derision and/or mockery of the concept of an online party.
A party, of course, is a gathering: an event where people come to a location in order to enjoy themselves with other people. When such an event takes place online, some elements of the event can be more awkward: everyone is in the same "room," so to speak, where chatting with a select group of people is much more difficult; people are prone to technical difficulties which limit their ability to participate in the event; people cannot share food or beverages with others; and so on.
Since the pandemic began, events have had to adapt to online environments, which, as I'm sure you've experienced, have a hard time surpassing that beloved human interaction. Plus, with the party being a murder mystery party, one would seemingly have to put on a costume only to sit in front of their computer the whole time. Obviously, this is not ideal. Some people, like the speaker, also probably find it awkward and/or strange to have such an event online in the first place.


How to browse Internet in Samsung Galaxy Fit using Broadband in Windows 7?

Question: I have a Samsung Galaxy Fit smartphone and want to browse the web on it using BroadBand connection (the one i use for my pc connection to Internet) in Windows 7.
Comment: possible duplicate: http://android.stackexchange.com/questions/2298/how-to-set-up-reverse-tethering-over-usb
Comment: i have checked that question and there seems no solution to that problem .There is an answer but its not working properly and question posted was one year back
Answer: From everything I have read about this topic, it is possible to do on a linux machine, but not with a windows machine. this could be because of something with ADB on windows, or the USB drivers for windows.
Here is the info (note that this reference was done with a Nexus One):

Requirements:

Android 2.2 (or an older version with a root tethering app)
ADB from Android SDK, or a rooted Android 2.2 with terminal in root mode

STEP 1:
Device: Connect USB cable and activate USB Tethering. You should see on linux new network interface.
STEP 2:
On Linux Computer, setup a bridge:

usb0 is the new network intreface
eth0 is the main interface connected to internet (or a gateway)
$ sudo ifconfig eth0 0.0.0.0
$ sudo ifconfig usb0 0.0.0.0
$ sudo brctl addbr br0
$ sudo brctl addif br0 eth0
$ sudo brctl addif br0 usb0
$ sudo ifconfig br0 up
$ sudo dhclient br0

See Network Connection Bridge Help to setup bridges
STEP 3:
Setup usb0 interface of your phone. You have to options:

From your computer, execute:
./adb shell netcfg usb0 dhcp
Or in a root terminal on your phone, type:
su
netcfg usb0 dhcp

You should now be able to connect to Internet on your phone using your computer's Internet connection.
Try to do a ping www.google.com to be sure
STEP 4:
To shut down the reverse-tethering, first unbridge interfaces on your computer:
<code>$ sudo ifconfig eth0 down
$ sudo ifconfig usb0 down
$ sudo ifconfig br0 down
$ sudo brctl delbr br0
$ sudo ifconfig eth0 up
$ sudo dhclient eth0
</code>
Then on your phone, uncheck the USB Tethering option
Comment: i am using a DSL connection and upon running sudo ifconfig eth01 0.0.0.0, i got this
SIOCSIFADDR: No such device,so i renamed the connection to eth0 ,then it worked fine
Comment: on running ./adb shell netcfg usb0 dhcp ,i got error: device not found
Comment: i didn't switch off usb tethering
Answer: The best and simplest idea in the long run would be to get a wireless broadband router that also supports ethernet (wired networking). Your pc can still use cables and your android phone just connects to it using wi-fi.
Without a wi-fi router you still have a few more options that work with Windows, as long as your pc has wi-fi (which you can get using a simple USB network card that costs less than 20 USD). In this case you have a few options (in order of recommendation):

Use software to turn your pc into a wifi router that shares it's internet connection. Instructions are available here.
Setup an ad-hoc network with Windows and then root your android phone to enable it to see ad-hoc networks using the instructions found here.
Use Wi-fi Direct which is a new protocol that'll work with Android 4.0 and Windows 8 (not very helpful, I know).


Older rental home with fake wood look floor- dull, how to shine/polish?

Question: We moved into a rented house last summer, it has "fake wood" floors - not sure of the brand or type, but the place was built about 20 years ago. We have 3 big dogs, and between their paws and other traffic, the floor just always looks dull. Some areas appear to have been damaged by water/flooding under past tenants.  I have tried the vinegar in water, rubbing alcohol, etc. remedies and it still looks dull and filmed. Since it IS a rented house, I do not want to do anything that will either make the floor worse, nor do I have any intention of removing and replacing. I have read that you can't use products like "Mop'n'Glo" or "Future" on these, so what options do I have?
Answer:
Use a liquid wax removing floor cleaner
rinse the floor completely clean with a mop
apply traditional liquid floor wax with an applicator or soft clean string mop

The floor will have a nice shine. This is how commercial floors in department stores look so nice and shiny. The drawback is that this has to be repeated every so often depending on traffic and abuse.
Answer: The top layer of a no-wax floor is applied in the factory, and is designed to last a specific period of time before it breaks down and wears out. After that happens, the inner layers of the flooring become exposed, and this is what gives the floor a dull appearance. Once this top layer is worn out, there is not much that can be done to restore its appearance.
The flooring is around 20 years old, which is near the end of the expected lifetime of this kind of product. You should avoid using harsh chemicals on it such as ammonia, bleach, vinegar, or alcohol. Instead, you should only use a gentle cleanser that is designed for no-wax floors. Harsh chemicals may damage the floor more, and give it an even duller appearance.
However, there are specific products on the market which in theory are supposed to restore the shine. I do not have any experience using them, but they could work. A quick search brought me here: http://www.acehardware.com/product/index.jsp?productId=1423617
I am not sure how well this product works, but it is formulated for Armstrong floors, which are fairly standard.
Answer: I totally agree with Jimmy Fix-it. Yes, frequent Mop & Glow-ing can be a pain. But, the only other option I know of is to strip it like Jimmy Fix-it said & then Polyurethane it like a wood floor, this would last much longer. You'll need to get a Flexible Poly or have to buy a Flex Additive to mix into the Poly, so it doesn't crack all over...IF it even has any give left in it, they're usually very stiff & brittle at this age.


Published pages missing

Question: All my published pages are missing from my wordpress. They are still online on my website (chrisjscambler.com), e.g. I have home, research, and teaching active online; but they are not available to edit in wordpress. They were all there until recently! any suggestions?
Comment: It's not possible to say anything about the circumstances because you are offering no details at all. "They were all there until recently!" is not exactly what a developer should look for. Which version are you using, are there any cleanup plugins installed etc. important things, which you don't provide.
Answer: Generally when content is missing it is often related to caching plugins. One of those plugins is OptimizePress which can sometimes conflict and make it seem the content is missing.
Here is what you can try:

Deactivate all plugins and check again.
Ensure the server has no caching enabled by asking your hosting
provider.
Check to see if your font is not the same color as your background.

If all of that fails, you can ask your hosting provider to see if they have a backup of your site to restore your pages.

Published pages missing


Automatic way to have a good initial guess for the iterative methods ( newton method) and for high dimensional nonlinear problems

Question: I am solving a variety class of nonlinear systems where I need to reduce in optimal manner the number of iterations of either the newton or modified newton method. For this end I am trying to figure out an automatic way to have a good initial guess for the iterative methods and for high dimensional problems. For one dimensional problems, I know that we can use the bisection method to have a good guess for the newton method which is not so practical for high dimensional problems. So I am wondering if there are other methods for the multi-dimensional case.
Comment: unfortunately, there is no universal techniques to provide a *good* initial guess. to be sure, you need to implement globalization techniques, like line search or trust region.
Answer: Suppose that you have $n$ equations for $n$ unknowns of the form $$f_i=f_i(x_1,x_2,\cdots,x_n)=0$$ I think that the fastest way to solve is to minimize function $$\Phi(x_1,x_2,\cdots,x_n)=\sum_{i=1}^n f_i^2$$ and not use Newton-Raphson which, as you wrote, can be slow.
If the solution is unique, no problem.
Generating good starting values is too much problem dependent to get an answer. May be, you could provide an example.
Comment: to minimize $\Phi$, you usually apply some kind of Gauss-Newton type methods. There is no free lunch :)
Comment: @user251257. Yes but it is much more stable and there are plenty of minimization methods which are totally available.
Comment: I would not say more stable. but one can introduce globalization techniques in a natural way. it may still perform poorly, if you are far away from optimum.
Comment: I agree with you. This could be the start of a very interesting discussion. May I confess that this is the way I always solve systems of nonlinear equations.
Comment: well, the Newton step and the gauss Newton step are the same, if the Jacobian is non singular. so you aren't doing something wrong. however the condition for the gauss Newton system is worse. that's all.


How to connect to Redis cache via ssl in DXA 2.0?

Question: We have client and Redis which configured to use ssl.
What should I set in cd_client.xml to get connection with Redis via ssl?
Comment: Vitaly , Welcome to Stack Echange , Please let us know the Tridion Version and leyt us know is your web app is .Net or Java
Answer: SDL Documentation  reference :
Configuring web application caching (Java) ->  Link
Configuring web application caching (.NET) -> Link
Refer to this link  for more  details
Answer: SDL DXA does not support Redis Distributed Cache.
"Regarding the distributed Redis caching, note that DXA is a framework, for which RWS provides options, and which customers can tailor as per their business requirements.  The distributed Redis caching is an option to configure and implement.  If there are specific implementation questions which are not clear, we can ask for clarification on this.  DXA support is offered via a PS engagement subscription, but DXA itself is not a core product offering."


Solving Non Negative Constrained Least Squares by Analogy with Least Squares (MATLAB)

Question: There is a least-squares problem Ax = b. It can be solved using backslash in Matlab (x = A \ b).
Let's assume that I have the same problem, but all x must be non-negative (>=0). How can I solve this problem by analogy with the previous one (without non-negativity constraints)? I think it can be somehow connected with the active set method.
I know that the non-negative least squares problem can be easily solved with Matlab Optimization toolbox or CVX or in many other ways. But still I'm curious about solving it by analogy with a straight-forward least-squares method. The idea is to make somehow from non-negative least-squares regular least squares.
Could anyone help me please?
Comment: Is $A$ full rank? What are the dimensions of $A$?
Answer: "Straightforward" least squares cannot include constraints. It has a simple function to optimize, the sum of squared residuals, and that's it.
Exactly because of that, the solution $x$ can be found by means of linear algebra, i.e. it is the result of applying a linear operator to $b$. This linear operator is described by the matrix $(A^T A)^{-1} A^T$ if the system has a unique solution; if not, the pseudo-inverse $A^-$ defines a linear operator that gives the minimum-norm solution. Though it is recommended to use the backslash operator in Matlab for numerical reasons, that doesn't change this basic idea. As soon as you introduce constraints what you are doing is no longer "least squares", and the solution is no longer given by a linear operator applied to $b$.
To my knowledge, the task of optimizing a quadratic function under linear (equality or inequality) constraints is the subject of quadratic programming.
Answer: The problem - Non Negative Least Squares is a Convex Optimization problem yet it doesn't have a closed form solution.
Yet, since it is a Convex Optimization problem one could use many methods to solve it efficiently:

Transformation into LP Problem.
Using Interior Point Method.
Using Projected Sub Gradient Method.

The last method can be viewed with connection to the classic Least Squares problem.
Solving regular Least Squares problem using Gradient Descent is easy.
How will it be different with the constraint applied?
Well, you will have to project the solution of each iteration onto the set of the constraints.
Here is the code:
%% Solution by Projected Gradient Descent

vX = zeros([numCols, 1]);

for ii = 1:numIterations
    vX = vX - ((stepSize / sqrt(ii)) * mA.' * (mA * vX - vB));
    vX = max(vX, 0);
end

The full code and validation against CVX is in my Mathematics Q561696 GitHub Repository.
Fast Algorithm for the Solution of Large Scale Non Negativity Constrained Least Squares Problems
There is a paper called Fast Algorithm for the Solution of Large Scale Non Negativity Constrained Least Squares Problems. The ideas there might be used here. The MATLAB Code is given as well - FCNNLS - Fast Combinatorial Non Negative Least Squares.


Trouble converting a path/fill to transparency in illustrator

Question: I have an vector image in b/w, and I want to convert black to transparent in AI.  I have a layer that I filled with red behind my image so I can see what is white and what is transparent.  I select the black path or the black fill, then click on the color window, and select the transparent (white square with line through).  The black turns to white rather than red, I think because the black parts of the image are on top of a white background.  Is there another way to make the parts that are currently black transparent?
Comment: "I think because the black parts of the image are on top of a white background." Why not make that white part transparent...? Is it a raster image and not a vector? Not sure I understand what's the issue then and what's so complicated. Also read about "pathfinder" and see if you can clean-up your vector to get more control.
Answer: May I ask thy not make the black layers, red?
Anyway, you can always "cut" the black shapes out of the white shape with Pathfinder > Minus Front.
To do them all at once you need to make sure that all the black shapes are in a single group and in front of the white shape. Select them all and hit Minus Front.
Update
In order for this to work, you must:
Have all the black objects inside a single group.

Copy the entire group.
Select the black objects group and A SINGLE WHITE OBJECT.
Hit Minus Front.
By now the black objects must've been cut out of the single white one
Remember when we copied the entire blacks group at point 2? Now pres Shift+Ctrl+V (Paste in place.)
Do steps 3,4,5,6 all over for each white remaining object that you want to cut the blacks out of.

(I am adding this second update cause the answer above depends on your objects arrangement inside layers)
As far as I can see you have 3 main objects, the Hawk, the G and the
Ribbon. To make things simple:

First Minus front applies to the ribbon, select the white ribbon and the blacks that are over it and hit Minus front.
The second Minus front is between the Hawk white and Hawk blacks.
The third is between the G and the copy of Hawk blacks.
Comment: Your first suggestion was right on.  Perfect.  That worked well.  I had tried the pathfinder minus front, and it got rid of blacks but they showed up as white, not red.  Not sure why.
Comment: @Nancy In order for this to work, you must: 1. Have all the black objects inside a single group. 2. Copy the entire group. 3. Select the black objects group and A SINGLE WHITE OBJECT. 4. Hit Minus Front. This only works well if you have a single white object. See my updated answer for the rest


Fama-French vs. Arbitrage Pricing Theory of Ross

Question: Is there a specific reason for why Fama-French papers on CAPM extensions do not refer to APT of Ross? In textbooks, APT is always an extension of CAPM and the foundation of extending the set of risk factors beyond market portfolio. However, I do not see this explicitly stated in Fama-French papers.
Comment: You might be in interested in this video from [John Cochrane](https://www.youtube.com/watch?v=8bHuTruzENM&t=1s) about ``What is the FF3 model?''
Comment: I have heard that Fama French got their idea from the ICAPM model of R. C. Merton and not from the APT model of Ross. But who said this I don't know.
Comment: Yes, the origins of their approach are puzzling to me. For example, yes, small cap firms outperform large cap firms. But why does this result in (S-L) variable that they construct? Why don't they take, say, the fraction S/L as the factor.
Answer: First, Fama French is not a model.  It is a falsification of the Capital Asset Pricing Model.  The APT is not an extension of the CAPM.  It is conceptually similar, but it is laid upon a different conceptual framework.
Let us begin with the Fama-French.  It is not a model.  It does not describe the behavior of humans.  The Capital Asset Pricing Model does describe the behavior of humans if it is true.
Fama and French added variables, probably incorrectly called factors, to the CAPM as a test of the CAPM.  If the CAPM were true, then the slopes of the added variables should be zero.  They were not.
Now, this is where it all gets a bit strange.  In 1940 Abraham Wald set the foundations for what is now called Decision Theory.  There are two branches of decision theory, a Bayesian and a Frequentist branch.
Both the CAPM and the APT are Frequentist models.  However, all admissible models are Bayesian models.  Frequentist models are admissible if they map to a Bayesian solution either at the limit or in every sample.  Admissible Frequentist estimators are Bayes estimators.  That is the linkage between the two interpretations of probability.
There is no requirement that an estimator is admissible, of course.  The sample median of the normal distribution is not admissible under squared loss, but that doesn't make it less valid of an estimator.  It just isn't an admissible estimator.
In Frequentist decision theory, you have an acceptance region and a rejection region.  If the result of an experiment puts the statistic of interest in the acceptance region, then you accept the null as if true.  If it is in the rejection region, then you reject the null and accept the alternative as if true.
In rejecting the CAPM, economics is to behave as if the Fama French alternative is true, subject to further exploration.  So, one should, in the next case, start with the Fama French as the null model and then explore alternatives.  If the Fama French is not rejected often enough, then it should be accepted as if true.
The problem is that Fama-French does not work out-of-sample.  So it rejects the CAPM, but it also rejects itself.
The APT is a different creature.  It is built off of the idea of orthogonalizing variables to force compliance with the requirements of regression.  As such, its error terms do not have the same interpretation as CAPM error terms.  The APT is not an extension of the CAPM and so Fama-French does not falsify it.  It is falsified by other research.  It also has never passed a validation test.


I can not use my play store app

Question: I want to log in my play store app but it's not letting me log in instead it's asking me redeem your code:
Answer: Make sure you have internet connection. Such screen appears when there is no internet connectivity. As I can see from the screenshot, that you are connected to a WiFi, make sure internet is available from that source.
I have recreated the similar situation. Connected my device to a WiFi which has no internet connectivity; Opened Play Store and this is what I got.

Screenshot (click for larger variant)
So, just connect to a stable source of internet and you will be good to go :)
Comment: @DeathMaskSalesman yeah, did that :)
Comment: You may want to edit your picture in order to hide your email address.

I can not use my play store app


Which test should be used when paired data (pre/post treatment) have different distributions?

Question: My question is if data are in paired groups (before and after treatment), where the pre-treatment group is normally distributed and the post-treatment group is not normally distributed (i.e. it is skewed), then which test should be applied? Is the Wilcoxon sign rank test appropriate?
Answer: The Wilcoxon sign rank test is appropriate. However you should be careful in your interpretation of the test.
In its most general form, the sign rank test is a test for stochastic dominance. That is, strong enough evidence will lead to a conclusion that a random observation from the pre-treatment group has a greater than (or less than) 50/50 chance of being larger than a random observation from the post-treatment group. The null hypothesis is that 50/50 chance, or: H$_{0}\text{: P}\left(X_{\text{pre}} > X_{\text{post}}\right) = 0.5$, and H$_{\text{A}}\text{: P}\left(X_{\text{pre}} > X_{\text{post}}\right) \ne 0.5$.
Under conditions where (1) the distributions in both pre- and post-treatment are the same shape, and (2) differ only in the central location of that shape (i.e. they are merely shifted with respect to one another, not 'stretched out' with different variances), then the Wilcoxon sign rank test can be interpreted as a test for median difference, with the H$_{0}\text{: }\tilde{\mu}_{\text{pre}} - \tilde{\mu}_{\text{post}} = 0$. However, these more rigid assumptions clearly do not obtain in your data, so you would interpret the results of the sign rank test solely in terms of stochastic dominance.
Comment: Indeed, if they have the same shape, the signed rank test can as legitimately be interpreted as a test of means (as long as means exist), just as it can be a test of medians, or 10th percentiles, or any number of other location-measures.


Java using Mod floats

Question: I am working on an exercise in Java. I am supposed to use / and % to extract digits from a number. The number would be something like 1349.9431. The output would be something like:
1349.9431
1349.943
1349.94
1349.9

I know this is a strange way to do but the lab exercise requires it.
Comment: fair enough, apologies for the harsh answer.
Comment: It's legit to ask questions from your homework, but you should add the "homework" tag.
Answer: Let's think about what you know.  Let say you have the number 12345.  What's the result of dividing 12345 by 10?  What's the result of taking 12345 mod 10?
Now think about 0.12345.  What's the result of multiplying that by 10? What's the result of that mod 10?
The key is in those answers.
Answer: if x is your number you should be able to do something like x - x%0.1 to get the 1349.9, then x - x%.0.01 to get 1349.94 and so on.  I'm not sure though, doing mod on floats is kind of unusual to begin with, but I think it should work that way.
x - x%10 would definetly get you 1340 and x - x%100 = 1300 for sure.
Answer: Well the work will be done in background anyway, so why even bother, just print it.
float dv = 1349.9431f;
System.out.printf("%8.3f %8.2f %8.1f", dv, dv, dv);

Alternatively this could be archived with:
float dv = 1349.9431f;
System.out.println(String.format("%8.3f %8.2f %8.1f", dv, dv, dv));

Answer: This is a homework question so doing something the way you would actually do in the real world (i.e. using the format method of String as Margus did) isn't allowed. I can see three constraints on any answer given what is contained in your question (if these aren't actually constraints you need to reword your question!)

Must accept a float as an input (and, if possible, use floats exclusively)
Must use the remainder (%) and division (/) operator
Input float must be able to have four digits before and after the decimal point and still give the correct answer.

Constraint 1. is a total pain because you're going to hit your head on floating point precision quite easily if you have to use a number with four digits before and after the decimal point.
float inputNumber = 1234.5678f;
System.out.println(inputNumber % 0.1);

prints "0.06774902343743147"
casting the input float to a double casuses more headaches:
float one = 1234.5678f;
double two = (double) one;

prints "1234.5677490234375" (note: rounding off the answer will get you 1234.5677, which != 1234.5678)
To be honest, this had me really stumped, I spent way too much time trying to figure out how to get around the precision issue. I couldn't find a way to make this program work for 1234.5678f, but it does work for the asker's value of 1349.9431f.
float input = 1349.9431f;

float inputCopy = input;
int numberOfDecimalPoints = 0;
while(inputCopy != (int) inputCopy)
{
  inputCopy = inputCopy * 10;
  numberOfDecimalPoints++;
}

double inputDouble = (double) input;

double test = inputDouble * Math.pow(10, numberOfDecimalPoints);
long inputLong = Math.round(test);

System.out.println(input);
for(int divisor = 10; divisor < Math.pow(10, numberOfDecimalPoints); divisor = divisor * 10)
{
  long printMe = inputLong - (inputLong % divisor);
  System.out.println(printMe / Math.pow(10, numberOfDecimalPoints));
}

Of my three constraints, I've satisfied 1 (kind of), 2 but not 3 as it is highly value-dependent.
I'm very interested to see what other SO people can come up with. If the asker has parsed the instructions correctly, it's a very poor exercise, IMO.

Java using Mod floats


how to Genrate pdf file when fetching data in to database

Question: how to Genrate pdf file when inserting Data into databas and Genrate pdf and also stored pdf into folder and also send mail to attachment for this pdf and send mail.
Comment: Welcome to Stack Overflow. You're unlikely to get help with these three questions. Why not? First of all, it's best to ask one question in each post. Second, you haven't tried anything. You're more likely to get help if you show some code. Third, your first question is very broad.  Please read this and [edit] your question.  https://stackoverflow.com/help/how-to-ask  (yeah, and nobody will mistake you for Mr. Gates, your picture notwithstanding.)
Comment: You can achieve that by writing code and then asking questions, not vice-versa
Answer: The one that I know of as being best is the FPDF. FPDF is a PHP class which allows generating PDF files with pure PHP, that is to say without using the PDFlib library. F from FPDF stands for Free: you may use it for any kind of usage and modify it to suit your needs.
It is a great open-source solution for creating all sorts of PDF layouts.
To send email with the generated pdf you can check on this StackOverflow question
See FPDF tutorials
And scripts


Why are flat sections printing rough?

Question: This is not a duplicate of Ender 3 first print some area is smooth but some is rough? -- that question has vertical, curved surfaces that are rough. My vertical, curved surfaces are fine; it is horizontal flat surfaces that are rough.
Second, I apologize for the dust on the prints in the video. I've been trying approaches on this for a week and dust has collected since that time.
I have an Ender 3 Neo and am using 1.75 mm Comgrow PLA filament. I'm using Cura as my slicer.
My problem is that all of my prints are fine, except some (the larger) horizontally flat sections print sandpapery to the touch. The walls are fine and smooth. Curved sections (such as a rabbit) are fine and smooth -- it is only horizontal surfaces that have this problem, and then only the larger ones.
By rough, I mean there are visually distinctive diagonal lines (which are on all my prints, smooth or not, so I assume are normal), but dragging my finger over them is like dragging it over fine-grained sandpaper.
My tests consisted mostly of Incarna Tokens.stl -- this is the picture above. It's a mostly rectangular container to hold pieces for a board game, with a flat bottom that prints rough and walls.
What I've Tried:

Original prints were with the default settings for the "Creality Ender-3 / Ender 3-v2" at Cura's super quality (0.12 mm) and had the problem.

Releveling the bed. I did this several times, using this Creality Service tutorial video: lower nozzle to 0 mm, adjust Z-offset until I could feel it rub against the nozzle but could still push and pull the paper in any direction. I then turned off the motor and manually moved the extruder to each corner, where I repeated it while turning the corner dials to raise/lower that corner. Things actually got worse.

I then tried the method again, but instead of turning off the motor, I used the motor to move the extruder to each corner. I got different results for the corners, which I don't understand. But adjusting using this method got prints going fine again... except for the horizontal sections which were still rough.

I tried adjusting the Z-offset and reprinting just on the center (not adjusting the corners) up by 0.05 mm and 0.1 mm, which only succeeded in making the prints stringier, and down by -0.05 mm and -0.1 mm, which just made them worse. I took this as evidence that my leveling with the paper was correct (enough).

I tried printing at each of the corners. No change, all prints came out the same.

I removed the filament and cleaned the nozzle with the needle provided with the printer. The pin came out with some tiny black specks but nothing that said "clog." Prints afterward were no different.

I adjust settings in Cura. Based on various things I read, I lowered print speed from 50 mm/s to 40 mm/s, I changed the flow to 97 % and then 95 %, I changed line width from 0.4 mm to 0.3 mm, I changed bed temperature from 50 °F to 60 °F (nozzle temperature stayed at 200 °F), I lowered fan speed from 100 % to 50 %, and I did combinations of these things. None of these had a noticeable impact other than the print speed and line width making it take longer.

I turned on ironing in Cura. This worked, but only sort of: 2/3 of the horizontal surface did not have diagonal lines and was completely smooth, a strip around the edges (the ironing offset) had diagonal lines but was still smooth, but 1/3 of the print still had diagonal lines and remains rough.  If the ironing completely worked it would solve my problem (I don't care about diagonal lines at the edges), but it only seems to be a 2/3 solution or so.

I adjusted ironing settings (following some page that I can't find anymore). I turned on monotonic ironing order, increased the line spacing from 0.1 mm to 0.2 mm, increased ironing flow from 10 % to 15 %, and increased ironing speed from 16.66 mm/s to 30 mm/s, then 50 mm/s, then 70 mm/s. None of these solved the problem that about a third of the print remained rough.

I measured the prints for X/Y dimensional accuracy. I don't have calipers or a precise tool, just a ruler and my eyeball, but they seemed fine. I also printed xyzCalibration_cube.stl -- a 20 mm cube -- to test the Z accuracy, which to my eyeball, is also fine. Vexingly, even back to entirely default settings / 0.12 mm print speed, the calibration cube is smooth on all sides, including the horizontal top, which still has the diagonal lines but feels smooth to the touch like I want.

I printed some other prints. The default rabbit print the Ender comes with (no horizontal flat surface, just curved surfaces) prints fine. Small horizontal surfaces (the cube, all of these Gloomhaven standee prints) print fine -- diagonal lines but smooth to the touch. Larger horizontal surfaces (like Dahan_Tray_thin.stl) continue to print rough.   I checked the large surfaces to see if they start smooth in a corner and then get rough, but no, the roughness is consistent across the entire surface.

I theorize, but do not have any experience to back it up, that this happens because the larger flat area means more elapsed time between layers, but even if that's true I don't know how I would counteract it. Looking at the closeup pictures, it seems like the line ridges are raised, but then why doesn't it happen on smaller prints?
So I turn to you. How do I stop my large horizontal prints from being sandpapery?
Comment: You have used links that force a download (which some users may not like). Please [edit] the links to the page that the file is on so individual users can download it themselves if needed. It would help a lot if you were to include photos of your printed models so we can see what is happening.
Comment: @agarza Thanks for reading this. I have adjusted the links to the files pages instead of the direct downloads and added pictures. Hope this helps.
Answer: Many Ender3 printers have a curved surface. Leveling is not going to fix all problems here. That is why you might have difference in thickness. Only a mesh bed leveling sensor is going to help here.
It looks like while ironing, the head extrudes a little too much material in the process. That way the extra material oozes out through the sides. You say that you tried increasing from 10% to 20%, so I would try it with 3 or 0%.

Why are flat sections printing rough?


NOT able to use Xlrd module in python

Question: Question: i M not able to use xlrd module though i have installed the same???
Error obtained :
Traceback (most recent call last):
  File "D:\xlrd_1.py", line 1, in <module>
    import xlrd
  File "D:\Python31\lib\xlrd\__init__.py", line 345
    u"Consolidate_Area": u"\x00",
                      ^
SyntaxError: invalid syntax

Code :
import xlrd
print ("hi")

Some more description:

I m using python 3.1,
I have installed xlrd-0.7.1.win32.exe (md5) taken from
http://pypi.python.org/pypi/xlrd/0.7.1.
able to see the xlrd package in python\Lib\Site-packages
tried copying to include file also which didnt work.

Need help on this..searched stackoverflow for the same problem as well as else where i didnt find answer so posting the same
Appreciate for any help on the same
Answer: You are using Python 3.
But the XLRD library you are using is written in Python 2!
(I wonder you succeeded in installing it)
Try to use the package xlrd3 for Python 3

NOT able to use Xlrd module in python


initial value problem have infinity many solutions.

Question: How to show that if there is two solution of IVP( initial value problem) then it has infinite number of solution?
Answer: If $y_1$ and $y_2$ are solutions that are different at $t_1$, then you can follow backwards the initial value problem with $y(t_1)=y_3$ from any point $y_3$ in the segment $[y_1(t_1),y_2(t_1)]$. As this new solution is bounded by the first two solutions, it can be continued until it meets one of the bounding trajectories, from there continue using those. Thus a new different solution for $y(t_0)=y_0$.


Implement AES with 16 bit block size?

Question: Can we implement AES with 16 bit block size ?if so what are its advantages and disadvantages?Is there any rule AES has to be implemented with 128,192,256 ?Can we use AES for odd number of bits(17,33,37..) ?
Comment: You could use AES in FFX mode.
Answer: I am assuming that you wish to consider this for standard encryption tasks, and I am going to ignore the specific reference to AES and talk about general block ciphers (pseudorandom permutations).
The answer is that small block sizes are very problematic. In particular, they break when used for encryption of any reasonable amount of information. I will consider two concrete examples. In CBC mode, security breaks down after $2^{n/2}$ blocks, when $n$ is the block length. This means that you could not encrypt more than $2^8=256$ blocks, which is just 512 bytes. This is due to birthday collisions. However, it's actually worse than this. The probability of having a collision at less than 256 blocks is not so small, and at such small numbers it is very problematic. If you use CTR mode, then once again you have a problem since the nonce/IV has to be unique. Even if you are using this from fresh each time with a new key, and so just use a counter beginning at 0, you still have a problem that you can't encrypt more than $2^{16}$ blocks, which is just 128KB.
Regarding constructing such a small block cipher, this can be done using the techniques from format-preserving encryption. You use a Feistel, but you need many rounds with such a small block (also making it very inefficient). Specifically, you need 24 rounds of Feistel (this is the current recommendation but there is also a concerning lack of clarity regarding the exact security in this case).
Comment: could you please provide a reference for the 24 round unbalanced festeil you're writing about ? Thx
Comment: I was referring to a balanced cipher. But, just look at the format-preserving encryption literature as mentioned by @CodesInChaos.
Comment: I like the answer. Mathematically it's possible to adjust the Rijndael's parameters to fit more than the 3 standard sizes (the original proposal was with 5 sizes). For odd number of bits, you need an odd wordsize (originally 8 bits), but this will make you to build specific SBoxes for it. The box is a composition of two operations for whom you have to have some background. Also mixColumns will require an study to adjust parameters.
Comment: @srgblnch I strongly warn against making any changes to Rijndael (or even to AES). Once you look at other parameters or you make changes, all of confidence built by years of cryptanalysis goes out the window. This has been shown many times. You change the SBox and/or you change the mixColumns and you have no confidence whatsoever in the security.
Comment: Yes, you are right: don't change an algorithm to use it in production. Furthermore, don't implement your crypto because there are many audited libraries.
What I've said is _mathematically_ it is possible as well as it can be studied cryptoanalytically the repercussions of any difference.

Implement AES with 16 bit block size?


Tax benefit on Home Loan

Question: I own one flat (Staying in same flat) for which I am claiming tax benefit on home loan.
Recently, I have purchased one more flat, can you please tell me how can I claim the tax benefit for the home loan? (The loan amount is 15L only)
Answer: For the Second House, you can claim "Interest" on housing Loan to unlimited amount. You should have taken possession of the house. There is no benefit for Principal repayment. You would have to show actual rent or notional rent, property tax and then deduct interest payments. See below for calculation.
a   "Annual letable value or rent received or receivable
 (higher of the two, if let out for whole of the year, lower of the two if let out for part of the year)"
b   The amount of rent which cannot be realized
c   Tax paid to local authorities
d   Total (b + c)
e   Annual value (a – d) (nil, if self -occupied etc. as per section 23(2)of the Act)
f   Annual value of the property owned (own percentage share x e)
g   30% of f
h   Interest payable on borrowed capital
i   Total (g + h)
j   Income from house property (f – i)

Illustration:
a. Property let for rent at Rs 10,000 per month. Yearly 1,20,000/-
b. Tenant has defaulted and not paid for 2 months. Loss of Rs 20,000/-. Tenant is now evicted or is in process. Legal notice served etc.
c. Property tax to Municipal Corporation. Yearly Rs 10,000/-
e. Annual Gains from Property 1,20,000 less of Rs 20,000 and less of Rs 10,000. Property Gain of Rs 90,000/-
g. Misc expense to up keep the property. No receipt required. Standard 30% of income received. i.e. 30% of 90,000 [Assume 30,000 for simplicity of calculation]
i. Interest paid on loan for the year, say 40,000.
j. Total Gain on Property Rs 90,000 less of Misc exp Rs 30,000 and less of interest Rs 40,000. Final Value Rs 20,000
Thus you would need to pay tax on Rs 20,000 only.
Note: For point a; If you have not rented the house [or rented at nominal rate] you have to show that you received Notional rent as per Govt Ready reckoner rates.
Comment: As i understand total interest paid in the year - ( B & C )  can claim but can you please tell what do you mean by "The amount of rent which cannot be realized" & Tax paid to local authorities?
Comment: @Petes see illustration.

Tax benefit on Home Loan


Elliptic curve cryptography in java

Question: i want to implement ECC in java.whether jdk1.7 alone to implement it or need anyother open source like bouncy castle or JCE provider. if bouncy castle is used how to install the
package for it.i dont know exact procedure. pls say the procedure to implement it.pls kindly clarify my doubt.
Comment: Java 1.1.7? Or Java 7? There is no Java 1.7.
Comment: Any relation to the `asp.net` tag? Nah, will remove it.
Answer: But JDK 1.7 provides native
The Java SE 7 release adds the following features:
Elliptic Curve Cryptography (ECC)
A new native provider has been added to the Java SE 7 release that provides several ECC-based algorithms (ECDSA/ECDH). See Sun PKCS#11 Provider's Supported Algorithms in Java PKCS#11 Reference Guide for more information.
http://docs.oracle.com/javase/7/docs/technotes/guides/security/enhancements-7.html
Answer: You should have a look at Bouncy Castle - Using Elliptic Curves, there are some examples how to use it.
Answer: Even in Java 6, I couldn't get ECC to work through standard JCA APIs alone. I had to reference Sun's sun.security.ec.NamedCurve class to get the EC parameters initialized correctly, and I had to install the BouncyCastle as a provider as well.
From my experience, I don't think one can implement ECC code that is portable across security providers. While small, you'll have direct dependencies on BouncyCastle APIs.

Elliptic curve cryptography in java


Does anyone know what the intuition of H-volume is?

Question: For a 2-place real function $H$, H-volume of $[x_1,x_2]\times[y_1,y_2]$ is $H(x_2,y_2)-H(x_2,y_1)-H(x_1,y_2)+H(x_1,y_1)$. What is really the intuition of the H-volume?
Answer: The H-Volume is the volume contained by the rectangle $[x_1,x_2] \times [y_1,y_2]$ of a 3-dimensional function $H(x,y)$.  To visualize this, see the Figure
which is the contour plot of the independence copula (which is simply a 3-dimensional function with some special properties that make it a copula function).
The H-Volume is the volume contained within the box labeled $R3$.  However, remember that the Copula function is defined as the H-Volume of the copula function $H$ from $[0,u] \times [0,v]$.  Thus, $H(x_2,y_2)$ in reference to the figure would be the volume contained by $R1+R2+R3+R4$.  To get the region of interest, which is just $[x_1,x_2] \times [y_1,y_2]$, we must subtract out $R2$ and $R4$.  However, by subtracting out $R2$ and $R4$, we have also subtracted out $R1$ twice. We thus add $R1$ back into the equation (recall that $R1$ is included when computing $H(x_2,y_2)$.
To think about it in 3-D terms, see the Figure .  The H-Volume of this 3-D function, which happens to be the independence copula density, is the volume enclosed under the blue shaded area, where the points are given by the rectangle $[x_1,x_2] \times [y_1,y_2]$.
Comment: Regarding your last statement? Does it mean that $H-$volume is $\int\limits_{y1}^{y2} \int\limits_{x1}^{x2} H(u,v) \text{d}u\text{d}v$?
Comment: While in general, the H-volume may be defined as you put it, for copulas, the integral you have provided is not correct interpretation, if we view $H$ as the distribution function and $h$ as the density.
The H-Volume in reference to the copula is the integral of the copula density.  Recall that $C(u,v) = \int_0^v \int_0^u c(u,v) du dv = C(u,v)-C(0,v)-C(u,0)+C(0,0)$.  Similarly, for arbitrary bounds, it would be $\int_{v_1}^{v_2} \int_{u_1}^{u_2} c(u,v) du dv = C(u_2,v_2)-C(u_2,v_1)-C(u_1,v_2)+C(u_1,v_1)$.  I updated the figure above to show the copula density rather than the copula function.
Answer: The H-volume gives the the volume of some n-box (or hyper-rectangle) from some measure. Volume being generalised here for higher dimensions. When the measure is the Lebesgue measure, then the H-volume is our usual notion of length, area and volume in Euclidian space:

$V_{Lebesgue}([0,0.5]) = 0.5$ (length)
$V_{Lebesgue}([0,0.5]\times[0,0.5]) = 0.25$ (area)
$V_{Lebesgue}([0,0.5]\times[0,0.5]\times[0,0.5]) = 0.125$ (volume)
$V_{Lebesgue}([0,0.5]\times[0,0.5]\times[0,0.5]\times[0,0.5]) = 0.0625$ (volume)

It's useful in probability theory because it can be used to compute the probability mass in some n-box given a multidimensional cdf H.
The two dimensional calculation is the one you mentioned above:
$V_{H}([x_1,x_2] \times [y_1, y_2]) = H(x_2, y_2) - H(x_2, y_1) - H(x_1, y_2) + H(x_1, y_1)$
Pictorially:

Where the contoured lines are a bivariate cdf H.
The general formula is:
$V_{H}(J) = \sum_{\textbf{c}\; \in \; \text{vertices}(J)} \text{sign}_J(\textbf{c}) H(\textbf{c})$
where the sum is performed over all the vertices of the hyper-rectangle J, and with the sign of the sum element being:
$\text{sign}_J(\textbf{c}) = \begin{cases}
                \;\;1, & \text{if c has an even number of lower bounds}.\\
                -1, & \text{if c has an odd number of lower bounds}.
              \end{cases}$
The independence or $\pi$ copula ($\pi(u,v) = uv$) is the same as the Lebesgue measure.
There is a matlab function for performing this calculation in any dimension: https://github.com/AnderGray/Hvolume-Matlab


How is GRUB able to read it's config file on ext3 fileystem?

Question: I have read that GRUB can read ext2 filesystems and has modules for doing this. What is the location of the mod on a Redhat system and how about if the /boot partition is ext3/ext4 or other filesystem type?
Answer: The grub ext2 module also understands ext3 and ext4, as the differences are minimal.  The module itself is built into the grub core.img file ( when you are using ext[234] for /boot ), which is normally copied into the sectors following the master boot record, before any partitions start, and the code in the master boot record just loads those subsequent sectors.
Comment: I certainly wouldn't call the differences minimal. Certainly when compared to ext2 vs. ext3, the changes are significant. (http://kernelnewbies.org/Ext4)
Comment: @Adrian, they are relatively small, incremental changes that don't require many changes to the code to still be able to read.  The only change that really takes any work at all is understanding extents.
Answer: To answer the part of your question that's in the subject line, the executable code for this is kept in the initrd image. The initrd image can be loaded directly into the kernel at boot time, which is how the chicken/egg problem is solved for getting the code for reading ext partitions without needing to read the partition.
Regarding the filesystem choice for /boot.

Ext3 is backwards compatible with ext2 and primarily introduces journaling.
Ext4 is a major revision to the ext filesystem, brings many new features, and is not reversible without restoration of data and rebuilding the filesystem.

I don't really see a need to worry about using ext3/4 on /boot. I usually don't even bother with a separate /boot on my virtual machines and it works just fine as a part of my ext4 partitions. I wouldn't worry about using ext2 without journaling on /boot either, as you're not likely to have outstanding write operations going on in the /boot filesystem during a power cut unless you're upgrading your kernel.
The modules are kept in the usual place: /lib/modules//kernel/fs/. They're compiled into the initrd image for use by the kernel at boot time.
Update: Haven't found an official RedHat statement, but it's noted in Michael Jang's book that RHEL 6 no longer ext2 for /boot as ext4 is perfectly adequate and now the default filesystem for /boot. The Jang book also states that there are effectively NO differences between ext2 vs. ext3 except for journaling.
Comment: This misses the question.  The initrd holds files that allow the *kernel* to access the root filesystem, not grub.
Answer: Grub (0.9x) supports ext2 and ext3 but not ext4 (unless backward-incompatible features are turned-off).
Whereas, Grub2 (since 1.97) supports ext2, ext3 and ext4 with the same module [ext2.mod] which is located at /boot/grub2/i386-pc/ in Fedora 17 (32-bit)


What could be the cause of a washing machine hose coming loose?

Question: Ok, I'm not a rocket scientist but this has me stumped. I have a new hot water hose for my washing machine.  I replaced the O-ring on the faucet side of the the connection, tightened and went to use. After about 10 minutes of use, the connection becomes loose and starts to leak. I've tightened this to the point of pain in my hand. What could be the cause?
Comment: If you are tightening it with your hand that's the problem.  Use channel locks and compress the rubber ring.
Comment: Does your washing machine vibrate or make a lot of noise?  Do the threads on the faucet look OK?
Comment: Heat makes metal expand.  The female coupling on the hose will heat up, and expand faster than the spigot. This along with pressure in the lines, could cause the connection to loosen over time.  Tighten the connection using [Channellocks](http://en.wikipedia.org/wiki/Tongue-and-groove_pliers), to insure the connection is tight.
Answer: Washing machines vibrate - an inevitable side-effect of an unbalanced drum turning - so anything not very tight will work its way loose over time.
The clamps usually used to compress the seal/o-ring are designed to be tightened using a screwdriver, and you want to get these clamps really tight. The o-ring will deform quite a lot as you compress it, but it is designed to do that.
Also, before you put the hose on, make sure the surfaces which will connect together are clean and dry - this will help reduce slippage.
Answer: Before installation, remove the flat black rubber washers from the hose coupling and inspect them.  Do not use plastic washers.  They don't last long and aren't designed for a washing machine hose.  The general rule for connecting a washing machine hose's female swivel nut to the male water valve is "Hand tight and a quarter turn until snug with a pair of pliers or channel locks."  Take care not to cross thread the swivel nut on the washing machine's plastic solenoid inlet valves threads.
Jeff, why did you only buy one new hose, when manufacturers warn you to replace what I consider to be substandard washer hoses?


Did the general public know RoboCop was a cyborg?

Question: In the first RoboCop film, did the general public know that RoboCop was a cyborg? Or did they think he was a robot with a (partially visible) human face?
Comment: @Kyralessa: I don't think so. It happens in the first 15 minutes or so of the film and the tag line was, *part man, part machine, all cop*.
Comment: @Kyralessa You should really fix that.  Go rent it now!  Or buy a cheap DVD of it.
Comment: Ha, I had no idea that [this was topical](http://www.imdb.com/title/tt1234721/).
Answer: After posting this question and reading Eight Days answer, I think he may be right but for a different reason. From the script:

He's a cyborg, you idiot! He recorded every word you said. His memory's admissible as evidence!

This implies that cyborgs were not unusual in the RoboCop world and their memory even has a legal status. In the dystopian world of RoboCop, the public probably didn't care much, as long as crime was reduced.
Update: in this deleted scene, Bob Morton's first two answers to the journalist's1 questions confirm to the watching world that Robocop is indeed a cyborg:

Journalist: "Mr Morton, is this a man or is this a machine?"
Morton: "Well he's technically an integrated cyborg. I'd be reluctant to categorise him as either, to tell you the truth."
Journalist: "And what about his intelligence? What is his intelligence quotient?"
Morton: [Laughs] "That's a funny question. I mean his memory is computer assisted. And we don't refer to computers as particularly intelligent. Fast, effective? Yes. But intelligent, per se? No, I wouldn't think so."

1 A journalist who sounds suspiciously like the director, Paul Verhoeven.
Comment: @EightDaysofMalaise: My point was that, if his memory could be used as a testimony in court, then cyborgs would have some kind of legal recognition, meaning their existence was public. As soon as RoboCop's memory was used, his nature would be known publically.
Comment: @Wikis - I fail to see how his video testimony would need to be treated any differently than a shoulder-cam (http://vmlip.files.wordpress.com/2012/05/ashland1_may2012_edit.jpg) or boring old CCTV footage
Comment: The board knows that he's a cyborg, but that's because they built him. To the general public, did they know that from the discussion in the board room?
Comment: @Richard: Clarence Boddicker did not realise he was being recorded until Dick Jones pointed it out.
Answer: Strong leaning on yes.
In one of the news reports, the female anchor (played by Leeza Gibbons) introduces him with this:

Who is he? What is he? Where does he come from? He is OCP's newest soldier in their revolutionary crime management program. OCP spokesmen claim the fearless machine has crooks on the run in Old Detroit.

When OCP executive Robert Morton is interviewed on Mediabreak, he says this:

Here at Security Concepts, we're predicting the end of crime in Old Detroit within 40 days. There's a new guy in town. His name is RoboCop.

From these public facing news clips we can read that he is introduced as both a machine and a man. This strongly suggests that the general public then knows, or it's at least intimated, that RoboCop is a cyborg.
Comment: If anything, I'd say your first quote implies he is not a cyborg, since he is introduced as a "fearless **machine**".
Comment: Most characters interact with him as if he were a human cop, rather than an artificial intelligence. If I were confronted with a pure machine that nevertheless passed the Turing Test, I wouldn't exactly react the way the other Robocop characters do. I think his nature was known. Enough people inside OCP and the police knew it. Even if not acknowledged officially, it must surely have leaked out.
Comment: Throwing a he/she designation onto a machine makes it a bit muddy
Comment: Oh, I see, good point. Though I think "he" tends to be used of robots generally.
Comment: Yea, I think a lot of androids and significantly sophisticated AI (whether in a robot or not) are referred to using personal pronouns. It just depends on how human-like the personality seems and whether others treat him as a peer/equal or sentient being. It doesn't necessarily connote a cyborg or cybernetic organism.
Answer: The cops quote bye the shooting range refers tot both
cop1 : this Guy is really good ! Cop 2 : he is not a Guy he is a machine !
Comment: That could just be a figure of speech.


Choice of color - logo, scheme matches with error message color

Question: Most often than not, the scheme of the website has to match that of the logo. When the logo has a RED, on a page it becomes unavoidable not to have a RED colored alerts, warnings, error messages displayed. Some times, initial message itself could have certain alerts to be displayed and that floods the site with RED, AMBER. Too many colors increase friction and reduce the user experience. Question: is there an alternate set of colors that can be used and break away from traditional colors? And by doing so, will the overall usability increase / decrease? Thoughts with research/real experience siting are most welcome. Thank you
Comment: Black and white are pretty strong in terms of warning and error messages (or even icons).
Answer: Using red for alerts and warnings can be tricky in general. A nice and short article about this is written by David Walsch: http://davidwalsh.name/dont-be-a-f00. In depth information about the systems tone of voice to users can be found in the book About Face 3 by Alan Cooper (a must read btw). One of the general rules is to don't let users feel stupid so try avoid combinations like 'you've made an error'.
For a solution to your problem I would look at other graphic possibilities than color. For example: you could place the message within a box that has a different background and/or border. Or you could make all system notifications italic for example. The most important thing, in my opinion, is that the notifications are easily recognized. It's therefor more important that the notifications are part of a coherent system, than that they are red.
Comment: First of all, thank you Ruudt for responding. The take away being 'easily recognized' message and that aligns with RED as other users have commented in David Walsh's page, is the source of confusion given that the background image/logo/theme color is RED. These two conflict and what I thought is to mellow down the theme/image to shades of RED rather than the same RED. This will resolve both conflicting concerns to great extent. Your thoughts?


'Hooch' - origins of the word

Question: I would like to know the real origins of the word (terminology) 'Hooch'.  I have done some research here and here.  However is there another point of view?  If I make my own, can I call it 'Hooch'?
Comment: Chattahoochee!!
Comment: English might be a better fit for this but I think it is OK here also.
Comment: Yup, I thought about that - if anyone wants it migrated that is not a problem.
Answer: Hooch means "cheap whiskey" and here is the origin of the term:

hooch (n.)
Also hootch, "cheap whiskey," 1897, shortened form of Hoochinoo (1877) "liquor made by Alaskan Indians," from the name of a native tribe in Alaska whose distilled liquor was a favorite with miners during the 1898 Klondike gold rush; the tribe's name is said by OED to be from Tlingit Hutsnuwu, literally "grizzly bear fort."
As the supply of whisky was very limited, and the throats down which it was poured were innumerable, it was found necessary to create some sort of a supply to meet the demand. This concoction was known as "hooch"; and disgusting as it is, it is doubtful if it is much more poisonous than the whisky itself. [M.H.E. Hayne, "The Pioneers of the Klondyke," London, 1897] - The Online Etymology Dictionary
Comment: Hooch was also used to describe the liquid that would separate from a sourdough starter.  This term was used by the sourdough gold miners in Alaska and the Yukon. ( they are called sourdoughs because of the sourdough starter they brought with them and used to survive on. ) They may have only had flour and water at times and thus sustained themselves on that alone, keeping a working sourdough starter they could pour off the hooch and get a little buzz. i would not recommend it. .

'Hooch' - origins of the word


Was tele-porting mentioned in ancient indian scriptures?

Question: As shown in various TV shows and movies, was teleporting done as per ancient scriptures.
Answer: Yep. Teleportation, or "Praapti" is one of the eight primary siddhis, or mystic perfections attained by rishis. Through Praapti, they can be transported to the place they desire.
Refer:
http://www.vedabase.com/en/sb/11/15/4-5
http://www.vedabase.com/en/sb/11/15/6-7
Comment: Prapti is about acquisition of objects.  I think mano-javaḥ in verse 6 is more like teleportation.
Comment: Oh, didn't notice that! Yes, Manojavah does seem more likely. Though I based my answer on the word Praapti, which is derived from 'Praap' which is used mostly in contexts of moving from place to place, like, "Praapya Dugdhodadheh tatam" means "Having reached the Ocean of Milk".
Comment: Also, since Prakamya is the siddhi for obtaining desired objects, Prapti can be used to denote desired destinations or desired places.


Why doesn't the minimum drag point meet the point at the best Cl/CD polar?

Question:
On the first picture, it shows that the minimum drag point is exactly the same as the maximum L/D ratio where it also supposes to be at The point as it shows on the second picture. However, according to the third picture, it doesn't look like the minimum drag point is at the maximum L/D on the second picture. Why does this happen?
Comment: simple answer: because lift is not constant and also increases with aoa
Answer: "Minimum drag" at 2deg in image 4.3 is just minimum Cd (coefficient not force). It is the most streamlined position and you will generate the least amount of drag here, for a given speed. You won't generate much lift though, if any. In fact, if you want to fly level (ie. at 1g) you will have to fly so fast that the drag will still become expensively large. Larger that if you were to fly at a more optimum angle of 5deg.
If Cl was constant over aoa, the best Cl/Cd would indeed occur at minimum Cd. ( a fixed quantity divided by the smallest ammount), alas Cl and Cd both increase with increasing aoa, reaching a best Cl/Cd ratio (in your example) at 5deg in image 4.7.
After that point, the Cd will increase a lot more than Cl, thus making the ratio worse.
Comment: What I confuse is that on the third picture,why is the minimum drag point not at maximum L/D and CL/CD?
Comment: forget that this is about aerodynamics, just focus on the graph: on any polar graph like the left image 4.3 , the highest ratio Y / X value will occur on the tangent from origin (ie 5 deg in your image, see 4.7) not on the apex of MinX ( at 2 deg in your image).This is true for any polar graph; It's math, not aerodynamics
Comment: Re "Minimum drag is just that, minimum Cd." -- actually, not.  For a different view see https://aviation.stackexchange.com/a/86327/34686.
Comment: Yeah, should have put that in quotes as I was referring to the label on the graph. I tried my best at rephrasing it
Answer: You need to distinguish between coefficients and the forces.
Coefficients are dimensionless numbers which are used to compare flow phenomena at different speeds, scales or atmospheric conditions. The force coefficients are the forces normalised by a reference area (to remove size effects), speed squared divided by two (to remove speed effects) and air density (to remove atmospheric effects). Mathematically speaking: $$c_X = \frac{X}{\rho\cdot\frac{v^2}{2}\cdot S_{ref}}$$ with $X$ being the force, $\rho$ being density, $v$ being air speed and $S_{ref}$ the reference area.
The lowest drag coefficient is at rather a low lift coefficient. In order to create enough lift to carry its own weight, the aircraft has to fly rather fast there. This high dynamic pressure at this polar point means that the total drag force is higher than at a polar point slightly above it.
At the point of best L/D the ratio between both forces reaches a minimum, so actually the lowest drag for a given lift is at this point.
Only if you disregard lift (say, in a vertical dive where the goal is to reach the highest speed) will the point of the lowest drag coefficient also be the point of lowest drag (at the same dynamic pressure). To generalize: The minimum drag point shifts between the maximum L/D polar point and the minimum $c_D$ polar point with the cosine of the flight path angle. Between 90° and 270° flight path angle (inverted flight) it shifts between the minimum $c_D$ point and the minimum L/D polar point (where lift is negative).
Comment: I guess the 4.3 picture makes this confusing when it says 'Minimum Drag' and points at the blue 2deg. It should say : Minimum Drag Coeficient. Actual drag Force at 2deg is higher than at 6 deg ( for a given unaccelerated flight)
Comment: Sorry, I couldn't get you. Do you mean if it is a level flight, then the minimum drag  point (only for level flight) is also the maximum L/D and CL/CD while in any other condition, the minimum drag point is at the point of minimum CD which was decided when the aero foil was made?
Comment: @RobertLo: Yes in case of level flight, but for climb and descent it is still very near the maximum L/D point since sufficient lift needs to be created. Only in the vertical dive is **no** lift required, and only then will minimum drag be where minimum $c_D$ is. The minimum drag point shifts between optimum L/D and minimum $c_D$ with the cosine of the flight path angle.
Answer:
On the first picture, it shows that the minimum drag point is exactly
the same as the maximum L/D ratio

This makes sense, at least in the context of linear constant-altitude flight, because Lift must equal Weight and therefore is constant, so if we maximize L/D, we also must minimize Drag.  (Also, if we're maximizing L/D, we're simultaneously maximizing Cl/Cd.)
But since airspeed is not fixed as angle-of-attack varies, it does not follow that by minimizing Drag, we are also minimizing Cd-- and that is the key to solving your quandry.
Despite the misleading label on the third graph, the flagged point is actually not the point of minimum Drag.  Rather, it is the point where the drag coefficient is minimized.  In the context of linear constant-altitude flight, where L = W but airspeed is free to vary as angle-of-attack varies, the point of minimum drag coefficient is completely different from the point of minimum Drag.

Why doesn’t the minimum drag point meet the point at the best Cl/CD polar?