SharePoint 2013 Video live streaming

Question: Does Sharepoint Server 2013 support live streaming of videos from other streaming servers?
Answer: Yes.

SharePoint 2013 has a built-in HTML5 media player that is used to play all video files that are compatible with the HTML5  implementation for the current browser. This means you can now play videos on mobile devices such as iOS that don't support Silverlight. If the format is not playable by the HTML5 player, then we use Silverlight. The video is auto-played when the user opens the video player page. The player streams video content using the BLOB cache, progressive streaming, and bit-rate throttling in the same manner as the SharePoint 2010 media player.

Ref: Enhanced Video Experience in SharePoint 2013

This also works using a simple Content Editor Web Part, where you edit the source of the webpart.
<code><video width="320" height="240" controls>
  <source src="otherserver.org/movie.mp4" type="video/mp4">
  <source src="otherserver.org/movie.ogg" type="video/ogg">
  Your browser does not support the video tag.
</video>
</code>
Ref: HTML  src Attribute
Answer: Yes, as noted in this Office blog article titled "Enhanced Video Experience in SharePoint 2013":

Provide a link to a video: Use this
  option to provide a link to a video file that resides in another site
  (such as videos from other SharePoint sites or file shares). It is
  important to note that your URL should point to a video stream file
  and not to a video player URL.
  [emphasis added]
Answer: No live streaming , but you can add videos wiwth correct format and turn on auto play and even optimize it with IIS Bit Rate Throttling extension or BLOB for smooth video streaming experiences. read more

Performance for video content management in SharePoint Server 2013
Tips: store image, audio, or video files

Some extracted data which shows the Supported Video Formats which can be played back without Silverlight.
Note that for example not all wmv files are the same and use more popular mp4 and webm formats to have the best experience
The Media Web Part uses HTML5 video and supports

asf, avi, mpg, mp3, mp4, ogg, ogv, webm, wma, and wmv video formats

The classic Silverlight Media Web Part supports

asf, mp3, mp4, wma, and wmv.

SharePoint 2013 Video live streaming


When to use field variable?

Question: Under what circumstance would you use field variable instead of local variable? I found it a bit hard to decide when a variable is used in 2 or more methods in a class. I tend to use local variables and pass them to another method.
Thanks,
Sarah
Comment: Related/duplicate: http://stackoverflow.com/questions/1794141/java-instance-variables-vs-local-variables
Answer: In object-oriented terms, does the variable make sense as an attribute of the object?  If so, you should make it a field variable.  If not, it can go either way.
Remember the Single Responsibility Principle -- well-designed classes should have only 1 responsibility, and thus only 1 reason to change.
Answer: A field denotes some kind of state related to an instance of your class.  For instance, a BankAccount could have a balance field.
You should never use a field to simplify passing data from one method to another method.  That's simply not its purpose.  Doing so also makes your methods intrinsically thread unsafe or require synchronization.
A local variable is just a temporary store of data used to support an operation being done by a method.  For example,
public void addInterest(double rate) {
    double toAdd = rate * balance;
    logTransaction("Interest", toAdd);
    balance += toAdd;
}

toAdd here makes no sense as a field since it is temporary to the operation, not a part of the account's state.
Answer: I would definitely not pass variables around to other methods unless there's a very specific reason. If the variable is used multiple times in the class, make it a field variable. This almost always makes your code much more flexible too.
In general, you can also think if the variable makes sense as a part of the class. That is, it makes sense to have a Car class have the variable numOfMiles, even if it's only used a few times. However, if one method is int GetAmountOfGasUsed(int milesThisTrip) it makes sense to pass in the miles variable as a local variable because the distance you travel is probably not specific to the car.
Answer: If the methods that use the variable need to modify the value as well, then by all means make it a field variable. But, if they only read the value, you can safely pass it around.

When to use field variable?


Delete Approval Process with the IDE or a similar tool?

Question: Was just wondering if there was an easier way, than having to track down all the records related to that original process, and then waiting for recycle bin to do the full physical delete.
Answer: The Approval Process cannot be pulled into the IDE, because there is no meta data access to Approval Processes just yet.
Hence why it has to be deployed manually.
Here's an idea to enable meta data for approval processes, much needed !
https://sites.secure.force.com/success/ideaview?id=08730000000BqjDAAS
Comment: I believe that Approval Processes may be in Spring 13 release, as mentioned at Dreamforce. (Safe harbor and all that)
Answer: While Approval Processes are not exposed in the Metadata API in order to delete the process definition in the IDE, the actual process workflow is exposed in the SOAP (Doc link) and REST APIs:
.
as a result, it's possible to delete a workitem (approval for a record) that is in process. It also means you can track down all the records related to the original process and delete them if you want including identifying ones already deleted.


Interior and Exterior lights randomly come on

Question: I have a 2012 Chevy Cruze and sometimes the interior dome lights and the exterior headlights come on by themselves. I think it only happens at night but that could just be cause it's easier to see. Also the radio is suppose to play until you open the door with the keys out and sometimes it flickers on and off a few times. Any ideas?
Comment: Some cars activate the headlights for a short time when you open the door. Does this model have that feature?
Comment: Welcome to Motor Vehicle Maintenance & Repair! It sounds like the body control module is going bad (or is bad). I believe GM uses the BCM for all of the functions you mentioned in newer vehicles.
Comment: Had one that th interior light would come on when a person of a certain mass sat in the passenger seat - broken spring shorting a wire...
Answer: You may simply have a faulty door switch that is turning on and off when it shouldn't.
Check that all the doors make the interior lights come on and go off when you open and close the doors.  You may also what to check the tailgate/trunk.
If one of them is not operating correctly then it's switch may need replacing.
Comment: This was my first reaction. If the headlights are programmed to turn on when the door is opened or closed, one common denominator is a door switch. Another common denominator is the BCM. I'd start with checking the door switches.
Comment: The headlights do not come on when opening the door and today when I turned the car off and took the key out it was trying to start on it's own.


Why do we say "attorney at law" and what is the difference between attorney and lawyer?

Question: Basically I was just struck with the term 'attorney at law' as being a somewhat odd English construction. I can't think of any other time where we refer to another profession this way. In other words, can one be an Attorney at Butchery, or perhaps an Attorney at Plumbing? Aren't all attorney's "at law"?
Which also made me wonder is there any difference between Attorney and Lawyer? I know that they are colloquially used to mean the same thing, but perhaps they were originally more (or less) specific? Or is it simply a redundancy?
Comment: I only now just read that other question. I suppose it is a "duplicate", but I like the answer provided below as it more thoroughly answered the question for me. That being said I hope that either the other question could be amended to include this answer or perhaps both questions could remain un-deleted. Regardless, I have my answer. Thanks all the same.
Comment: http://www.etymonline.com/index.php?term=attorney&allowed_in_frame=0 and http://www.etymonline.com/index.php?term=lawyer&allowed_in_frame=0
Comment: You need to specify what country/ies you're talking about. E.g. in the UK, the term 'attorney' is not the same as a lawyer and is used only in specific cases.
Comment: I agree it would be a good idea to merge the answers. The top answer in the dupe is far less detailed although concise.
Answer: This answers pertains to the United States, not Great Britain, nor perhaps Canada.
"Attorney" and "Lawyer" are, for most purposes, synonyms.
For questions of this nature, which involve some specialization and may involve jargon (in this case legal jargon or usage) one should consult a good specialist dictionary.  An excellent source for this is Black's Law Dictionary (or Ballantine's).  "Lawyer" is defined in Black's as follows:

"a person learned in the law; as an attorney, counsel or solicitor; a
  person who is practicing law."

The reason I say "for most purposes" is that as a non-lawyer I may be appointed to be your attorney (i.e. given "power of attorney") to act in some or all matters pertaining to you, but I may not practice law, or hold myself out to the public to practice law.  To do this I would need to be an "Attorney at Law" or a "Lawyer".
As to the prepositional phrase "at Law", the basic law of the United States remains English Common Law, especially as it existed at the time of the Revolution.  The prepositional phrases "at law" or "in law" hark back to this.  The only state of the Union which does not have Common Law as its basic law is Louisiana, which due to its origins as a French colony retains a form of Roman Civil Law. See Wikipedia.
By "basic law" I mean "law of the land".  It is the law that exists even if all statutes were to be repealed.  Most provisions of common law have been replaced by statute law, but it is still possible on occasion to revert to the common law.  An old acquaintance of mine who was a highly-knowledgeable non-lawyer one time managed to convince a judge that a particular statute did not apply in a case, and the court proceeded to treat the case as an "in Law proceeding", i.e. that the Common Law would govern.  Anyway, anytime you hear the phrases "at law" or "in law" it is the Common Law that is meant.  Usually, anyway.
Incidentally, some people have the idea that the Common Law does not exist any longer in the United States, but this is false.  Most states explicitly state in their statutes that the Common Law is still in effect.  This example from Washington State's "Revised Code of Washington" should suffice to persuade that this is the case.

RCW 4.04.010 Extent to which common law prevails.
The common law, so far as it is not inconsistent with the Constitution
  and laws of the United States, or of the state of Washington nor
  incompatible with the institutions and condition of society in this
  state, shall be the rule of decision in all the courts of this state.
Answer: An attorney is anyone who acts on behalf of an individual. A lawyer is someone who acts on behalf of someone for legal purposes, thus attorney at law. There can be many kinds of attorney but the word is seldom used outside of the phrase "at law".
Comment: People may prepare a document assigning "power of attorney" to someone else.


Is there a software that allows people to have different passwords?

Question: Is there such a software that allows you to enter different passwords. When you login with one of them you can see all your files, but when you put in the another one, you can only view selected files?
Comment: Your search keyword is "plausible deniability".
Comment: http://lmgtfy.com/?q=Plausible+deniability+
Comment: This isn't program to install. It describes what you want to have compressed in two words: "Plausible deniability". I mentioned it in order to help you find your own solution using search machines and while explaining it to other people.
Comment: Having different files and a password for each user sounds like your classic per user home directory. But since you are explaining in length that's probably not what you are looking for. You seem to want to allow different passwords, like if you would be forced to reveal your password that you can reveal one and whoever forced you would only see a bunch of innocent stuff?
Answer: You should elaborate on you true intentions. If you are trying to setup a local file share that you can edit and others can read then simply set the permissions of those files to readonly for others. If you are setting up an online file share like Dropbox then the process is the same.
Comment: I am not asking how to setup up a local file share. Here is what i meant: you have two passwords for one user( it is offline work). when the first password is entered, the person can view everything, however, if the second one is entered, the person only sees a bunch of stuff that you want him to see.say somebody of higher authorities and power forces you to tell them your password. then you tell them the second password and as they login to your account, they can only see limited things.
Comment: Unless you are custom creating something most systems use one username/password combination it is more secure.
Answer: What about using something like TrueCrypt? Don't know if this exists for Ubuntu and yeah, I heard that they stopped developing and say they are not 100% safe anymore, but if you don't have to hide things from the FBI/... this is more than enough. You can create virtal volumes that you save either as a file on your disk (you can also hide it e.g. in a video file) or in unpartitioned space on your disk. Any encrypted data created by TrueCrypt should theoretically look like random numbers and therefore your boss or anybody should not be able to see even IF you have encrypted data. But I don't know if it only exists (existed) for Windiws, though...
Comment: It does exist for Ubuntu: http://askubuntu.com/q/174872/75166 , there are two more things you should add to your answer: - If you loose your Trucrpyt password there is no way to recover your data. - Installing Truecrypt is just the first step, using the passwords from the Login-shell and having your home automount your volume is a different story.
Comment: They forked TrueCrypt into VeraCrypt and CipherShed, you should probably be looking into using those. Or just use the build in encryption of Ubuntu (ecryptfs or LUKS). http://veracrypt.codeplex.com/ https://wiki.ciphershed.org/
Comment: But he asked (at least it sounded like) for plausible deniability, so he wants to be able to grant somebody access to his machine, but this one could then NOT be able to detect IF there is actually any hidden data. I know TrueCrypt for Windows could provide this feature pretty well as I described above.

And @MadMike of course he must not forget his pw! If it would be possible to recover the encrypted data (at least without NSA supercomputers) nobody would use it, as he could also an encrypted zip folder. When he wants to automatically mount the volume with his boot pw it also loses its sense!
Answer:
Is there a software that allows users to have different passwords?

Yes, see How to configure Ubuntu as an LDAP client?.

When you login with one of them you can see all your files, but when you put in the another one, you can only view selected files?

No, never going to be possible. You need 2 users for this with each their own password where user2 only has access to part of the files of user1.  This is actually very typical of large organisations where individual users have access only to the information they need on a file server.
To accomplish this you need to set up a data directory (or data partition if you'll be adding more users afterwards) using groups where individual groups have access to certain directories.
If you want to "hide" just one particular directory or a bunch of files from another user (like dad) that has access to your password , just look at this answer: How can I easily encrypt a file?
Comment: I could do that. but it would not be 100% promising and accurate. You see my "dad" is going to ask me my password and I have to give him a password. and say he is an expert in finding files. And i want him to find nothing other than what I want him to( because of the password he got ). but thanks anyway.
Comment: [TrueCrypt](https://www.grc.com/misc/truecrypt/truecrypt.htm) is still a valid and mature package (thought the single developer has stopped maintaining it). *That one* can hide things in the free sectors of the hard drive (advanced feature, take [backups](http://askubuntu.com/questions/569679/whats-a-good-back-up-strategy-for-1-desktop-pc) before installing) and [RTFM](https://www.grc.com/misc/truecrypt/TrueCrypt%20User%20Guide.pdf) first!  ;-)  And the wife will never know...


Change of coordinates to solve an equation in partial derivatives

Question: Given an equation in partial derivatives of the form $Af_x+Bf_y=\phi(x,y)$, for example $$f_x-f_y=(x+y)^2$$ How do I know which change of coordinates is appropiate to solve the equation? In this example, the change of coordinates is $u=x+y$, $v=x^2-y^2$, why?
Comment: This is an inhomogeneous linear transport equation. You can solve it with the method of characteristics, I'm not sure where you got $v$ from though
Answer: lets write $\mathbf x = (x,y)^T$. The equation is the linear inhomogeneous transport equation,
$$ \mathbf a \cdot \nabla f =b,$$
where $f=f(x,y)$ and specifically $\mathbf a = (a_1,a_2)^T=(1,-1)^T$ and $b = (x+y)^2$, but I will continue almost as if I don't know what $\mathbf a$ or $b$ are.
I'll sketch out a theory("The method of characteristics") assuming you are given initial data, that works in a large generality. In particular, with very minor modifications you can also allow the coefficient $\mathbf a$ of the derivative to be a function, or even depend on $f$ (but not $\nabla f$).
Suppose we are prescribed initial data $f(x,0) = f_0(x)$. (more general initial data along a hyper surface is possible) Consider the family of ODEs that define the "characteristic curves"
$$\frac{d}{dt} \mathbf X(t;z) = \mathbf a, \quad \mathbf X(0;z) = \binom{z}{0} \\ \frac{d}{dt}  F(t;z) = b(\mathbf X),\quad F(0;z) = f_0(z) $$
These can be solved, by Picard-Lindelof.
In this case, $\mathbf X$ is in fact a globally invertible change of coordinates,x since  we can explicitly write
$$\mathbf X= \binom{z}{0} + t\mathbf a = \mathbf x \iff t= y/a_2,\quad z = x-ta_1 = x - ya_1/a_2$$
(the condition that $a_2 \neq 0$ is related to the fact that the initial data is prescribed on the $x$-axis: the important point is that $\mathbf a$ is not tangent to the hypersurface where the initial data is prescribed.)
Let's write the inverse map of $\mathbf X$ as $\mathbf Z$ with the explicit formula $$\mathbf Z(\mathbf x):=\binom{t(\mathbf x)}{z(\mathbf x)} = \binom{y/a_2}{x - ya_1/a_2}$$
One can now check that if we define
$$ f(\mathbf x) := F(\mathbf Z(\mathbf x))$$
then $f$ solves the original PDE. Indeed, by chain rule and inverse function theorem,
$$ \nabla f(\mathbf x)^T = (\nabla F)^T(\mathbf Z(\mathbf x)) (\nabla \mathbf Z)^T(\mathbf x)=(\nabla F)^T(\mathbf Z(\mathbf x)) ((\nabla \mathbf X)^{-1}(\mathbf Z(\mathbf x)))^T$$
If we hide the point $\mathbf x$ where the functions are evaluated, this is written perhaps more legibly,
$$ \nabla f^T = (\nabla F\circ \mathbf Z)^T ((\nabla \mathbf X)^{-1}\circ \mathbf Z)^T  $$
Then the dot product $\mathbf a \cdot \nabla f$ is
$$\mathbf a \cdot \nabla f= \nabla f^T \mathbf a = (\nabla F\circ \mathbf Z)^T ((\nabla \mathbf X)^{-1}\circ \mathbf Z)^T \mathbf a $$
Since $\mathbf a$ is precisely the first column of $\nabla \mathbf X\circ \mathbf Z$ (if we agree to write $t$ derivatives in the first column), $((\nabla \mathbf X)^{-1}\circ \mathbf Z)^T \mathbf a = \binom{1}{0}$. Thus
$$ \mathbf a \cdot \nabla f = (\nabla F\circ \mathbf Z)^T  \binom{1}{0} = (\partial_t  F)\circ \mathbf Z = b(\mathbf X\circ \mathbf Z) = b$$
as needed.
(See also Method of characteristics (quasilinear pde- nonlinear transport ),  Explaining the method of characteristics )
Answer: This is a linear PDE then
$$
f = f^h+f^p
$$
with
$$
f^h_x-f^h_y = 0\\
f^p_x-f^p_y = (x+y)^2
$$
for the homogeneous solution we have $f^h(x,y) = \phi(x+y)$ by characteristics method. Now the particular is obtained proposing for $f^p$ a polynomial form as
$$
f^p = a x(x+y)^2+b y(x+y)^2
$$
and after substitution we have
$$
f^p_x-f^p_y - (x+y)^2=(a-b-1)(x+y)^2=0
$$
so the solution is
$$
f(x,y) = \phi(x+y) + a x(x+y)^2+b y(x+y)^2, \ \ \mbox{such that}\ \ a-b=1
$$
NOTE
Regarding the change of coordinates we know one coordinate for sure which is $u = x+y$ but we need two coordinates so we choose the other as $v = x-y$ because $u, v$ form a valid (independent) coordinate system. We could choose instead $x+y, x+ a y$ with $a \ne 1$ as well.


ILS Frequency Assignment In Dual Nav Radio Setup

Question: With a dual Nav radio setup (On autopilot panel) does the ILS frequency of the runway you're about touch down on need to be entered into both radios or just one? Cheers.
Answer: It doesn't need to be entered in either receiver.
If you want the ILS info displayed on the #1 display, enter it in the #1 nav radio. If you want it on the #2  display, enter it in the #2 nav radio. If you want it displayed on both, then enter it in both. If you don't need it displayed - perhaps you're flying a visual approach - then you don't need to enter it anywhere.
Some procedures may require a particular setup, but in the general case it's up to the pilot.
Comment: Thanks for taking the time to answer as it's confirmed what I understood to be the case. A certain flight simulator states that the RWY ILS frequency needs to be entered into both NAV 1 & NAV 2 radios when flying an ILS/DME approach. I realise of course that the sim world and real world  don't always correspond exactly with each other @Ralph J


Image uploading issue Sharepoint Foundation 2013

Question: I'm trying to Edit a page, add a table to it and upload a picture.
What I'm expecting (and was getting before today) - to get that picture in the cell of a table which I can then change the size etc using the top bar above the ribbon for editing purposes.
What I'm actually getting - the picture gets uploaded to SiteAssets library, I get the window prompted to add in Title and E-mail and the actual picture is not appearing on the screen then.
I believe I've changed something in the Content Types for either Picture / Item while working on my picture library app. However, I can't understand what happened here.
Is there any chance to either set these default content types to their default parameters?
Answer: Verify the picture was properly uploaded to the site assets library and the link to the picture is pointing to the proper location
if the picture is on draft mode (due filling all the required fields) you might not be able to see it.
additionally i would recommend as a best practice to upload your images in a specific repository for images and the add the link to image from a SharePoint Location to your page
Comment: Thanks, Erin!
What's weird though - before I was able to add the image through Edit options, it would be saved to Site Assets library automatically and at the same time it would occur on the page straight away. It doesn't happen anymore for some reason. I've compared content types settings with out of the box SP2013 - it's all same. So I've definitely have something else incorrect here as the image now is only saved to the SiteAsset library and doesn't appear on the site view straight away
Comment: the normal behavior of SharePoint is to create a folder in the site assets, then a folder called "pages" or "sitePages", inside that folder a folder with your page name and inside of that is your image, check if you have permissions to all of those folders, it seems to me like you are not being allowed to publish to those folders anymore
Answer: Right, so after working on it for the full day I've finally fixed it with some help.
Basically it is what I thought - content types were screwed.
I used the command to run in SP powershell to reset all of the content types:
stsadm -o deactivatefeature -name Fields -url http://sitecoll -force
stsadm -o activatefeature -name Fields -url http://sitecoll -force
Ran successfully but didn't help to solve my issue.
I had a great chance to compare my modified SP page with fresh out of the box SP page and then updated the Content Types accordingly as how it is in OOTB version.
Still didn't sort my issue.
And then in the SP Designer we went to each site of the SP > Lists and Libraries > Site Assets > edit columns > deleted "E-mail" column that shouldn't be there at all (I think this what was causing the actual issue). Then went back to Site Assets, Content Types "Document" and then pushed changes to sites and lists.
I am now able to upload the image from my computer which automatically goes to the SiteAssets library and also gets displayed on the screen at the same time.
Thanks for advice though, it's good to know another way of working with those images!


How does one access apps on Android Wear 2?

Question: My Huawei updated to Android Wear 2 and now I can't find my apps. I have swiped in every direction but none appear. I cannot find a comprehensive manual of controls (though Google searches happily return scads of useless tips-and-tricks articles in long-form prose).
Answer: A single press of the primary hardware button now opens the apps drawer. Before the update this would turn off the screen.


How is the column space of a matrix A orthogonal to its nullspace?

Question: How do you show that the column space of a matrix A is orthogonal to its nullspace?
Comment: You should make your question self-contained (such that it is understandable without referring to the title)...
Comment: The following illustration might help: http://en.wikipedia.org/wiki/Kernel_%28linear_algebra%29#Illustration
Answer: What you have written is only correct if you are referring to the left nullspace (it is more standard to use the term "nullspace" to refer to the right nullspace).
The row space (not the column space) is orthogonal to the right null space.
Showing that row space is orthogonal to the right null space follows directly from the definition of right null space.
Let the matrix $A \in \mathbb{R}^{m \times n}$. The right null space is defined as $$\mathcal{N}(A) = \{z \in \mathbb{R}^{n \times 1} : Az = 0 \}$$
Let $
A =
\left[ {\begin{array}{c}
 a_1^T \\
 a_2^T \\
 \ldots \\
 \ldots \\
 a_m^T
 \end{array} } \right]$. The row space of $A$ is defined as
$$\mathcal{R}(A) = \{y \in \mathbb{R}^{n \times 1}: y = \sum_{i=1}^m a_i x_i \text{ , where }x_i \in \mathbb{R} \text{ and }a_i \in \mathbb{R}^{n \times 1} \}$$
Now from the definition of right null space we have $a_i^T z = 0$.
So if we take a $y \in \mathcal{R}(A)$, then $y = \displaystyle \sum_{k=1}^m a_i x_i \text{ , where }x_i \in \mathbb{R}$. Hence, $$y^Tz = (\sum_{k=1}^m a_i x_i)^T z =  (\sum_{k=1}^m x_i a_i^T) z = \sum_{k=1}^m x_i (a_i^T z) = 0$$
This proves that row space is orthogonal to the right null space. A similar analysis proves that column space of $A$ is orthogonal to the left null space of $A$.
Note: The left null space is defined as $\{z \in \mathbb{R}^{m \times 1}: z^TA = 0\}$
Comment: @aceminer I'm not the author of this answer, but I think I can say something. Frequently when we are using the convention that vectors are columns, we treat the row space as consisting of column vectors. This matches the definition given of the row space, where the $a_{i}$ are (column) vectors, and the $a_{i}^{T}$ are the rows of $A$; then $\mathcal{R}(A)$ is the space spanned by the (column) vectors $a_{i}$.  So $y$ and $z$ are both column vectors.
Comment: @Morgan Rodgers Can you explain the part on transpose? y transpose z to form 0. If i understand correctly y is a row vector and z is a column vector. If y were to transpose, it would become a column vector
Comment: Ah I see thanks
Answer: You can't show this: it is false. Take
$$\begin{bmatrix} 0 & 1 \\ 0 & 0 \end{bmatrix};$$
both its column space and null space are the subspace $\{(x, 0) \mid x \in \mathbb{R}\}$ (the $x$-axis, so to speak). I think you need self-adjointness (symmetry in the real case) to get this.
EDIT: Sivaram anticipated me.
Answer: The OP's question would have been well-phrased had he specified that the matrix $A$ is symmetric i.e. $A=A^\top$, in which case ${\rm colspan}(A)={\rm rowspan}(A^\top)={\rm rowspan}(A)$.  Now, consider the definition of ${\rm null}(A)$ as the space of all vectors $\mathbf{v}$ such that $A\mathbf{v}=\mathbf{0}$.  Letting $\mathbf{a}_1,\ldots,\mathbf{a}_n$ be the rows (and columns) of $A$, matrix multiplication tells us that $\mathbf{a}_i\cdot\mathbf{v}=0$ for each $i=1,\ldots,\dim(A)$.  Thus any vector $\mathbf{v}\in{\rm null}(A)$ is orthogonal to ${\rm colspan}(A)$.  It follows that ${\rm null}(A)\perp{\rm colspan}(A)$.$\square$


How to determine if this integral converges? $ \int_{1}^{\infty} \frac{\cos x}{x}dx $

Question: I should determine whether this is a convergent or divergent integral.
I need to use the comparison test but I don't find any intgeral that helps me figure this.
$$
 \int_{0}^{\infty} \frac{\cos x}{x}dx
$$
Comment: i'm so sorry, but i made a mistake and the integral is from 0 to infinity, not 1 to infinity (like i wrote before). i fixed it.
Answer: The proof is similar to the proof of conditional convergence of alternating series (monotonously convergent to 0 times alternating bounded = convergent). In fact, you can bound it by a discrete series:
$$a_n=\left|\int_{\pi (n-1/2)}^{\pi (n+1/2)}\frac{\cos x}{x}dx\right|\leq\frac{1}{\pi (n-1/2)}\left|\int_{\pi (n-1/2)}^{\pi (n+1/2)}\cos x\right|=\frac{2}{\pi(n-1/2)}$$
So the integral
$$\int_{\pi/2}^\infty\frac{\cos x}{x}dx=\sum_{n=1}^\infty (-1)^n a_n<\sum_{n=1}^\infty (-1)^n \frac{2}{\pi (n-1/2)}$$
converges.
There is a technicality of uniform convergence to consider (the question if the integral $\int^x$ for $x$ that is not a multiple of a period, doesn't wildly oscillate). However, I think that because the integrand is bounded from both sides by a function that monotonously converges to zero, it shouldn't be a problem.
The $\int_1^{\pi/2}$ part is finite and trivially convergent.
Answer: The integral is conditionally convergent.
Hint: To show the convergence, use integration by parts and absolute convergence of $\sin t/t^2$ (which would imply its convergence)
To show the integral is not absolutely convergent, break the integral into many parts. $\int_1^{\pi}+\sum_{n=2}^{\infty} \int_{(n-1) \pi}^{n \pi}$ for n=2,3,4,.....
Now, in the interval $\int_{(n-1) \pi}^{n \pi}$ $\lvert\frac{\cos y}{t}\rvert dt$ is greater than equal to $\int_{(n-1) \pi}^{n \pi}$ $\lvert\frac{\cos t}{k\pi}\rvert dt$ (the summation of which diverges)


A question on very ample line bundle and closed immersion

Question: Let $X$ be a projective scheme, $i:X \hookrightarrow \mathbb{P}^n$ a closed immersion, $\mathcal{L}:= i^*\mathcal{O}_{\mathbb{P}^n}(1)$ a very ample line bundle. Let $j:{\mathbb{P}^n} \hookrightarrow \mathbb{P}^N$ be a closed immersion and $\mathcal{L}':= (j \circ i)^* \mathcal{O}_{\mathbb{P}^N}(1)$. Is it true that $\mathcal{L}\cong \mathcal{L}'$?
Answer: It need not be true in general. For example, take $X = \mathbb{P}^1$, $n=1$, $i$ the identity map, $N = 2$ and $j$ the degree 2 Veronese map into $\mathbb{P}^2$. In this situation $\mathcal{L} \cong \mathcal{O}_{\mathbb{P}^1}(1)$ but $\mathcal{L}' \cong \mathcal{O}_{\mathbb{P}^1}(2)$.
Comment: Thank you. So, is there any condition under which $\mathcal{L}$ will be isomorphic to $\mathcal{L}'$?
Comment: Yes, I would say so. To cause them to be non-isomorphic in my example I needed a specific choice of map $j$. If instead I had chosen $j$ to embed $\mathbb{P}^1$ as a line in $\mathbb{P}^2$ then the line bundles would be isomorphic, and I believe this is true more generally, if you embed $\mathbb{P}^n$ as a linear subspace of $\mathbb{P}^N$. Perhaps there are weaker conditions than that, but I don't know them :)
Comment: I only have linear embedding in mind. Could you suggest a text to read this.
Comment: Hartshorne is certainly the standard text. I would suggest possibly learning the theory for curves first though from a book like Rick Miranda's if you haven't already.


When a speedster runs does everything become colder?

Question: So I was watching X-Men: Days of Future Past. In the prison break scene when Quicksilver deviates all the bullets, he first tastes whatever they were cooking in the kitchen. So it got me thinking, if his relative speed increases that means that the vibration of the particles on the soup (or whatever) become relatively slower. Since heat is strictly related to the vibration of the particles, does this mean that everything becomes colder relative to him?
Comment: Voting to reopen. The reason for closing states: "Questions seeking scientific solutions or explanations are off-topic ***unless related directly to a cited work of fiction***." The question is asking about the effects of a fictional superpower. It may be inspired by real-life science, but it certainly isn't satisfactorily answerable using real-world science.
Comment: @ApproachingDarknessFish And how are we supposed to answer with in-universe physics only? In fact, we'd be using real-world physics to answer it.
Comment: @Möoz No, you wouldn't, because real-world physics says that Quicksilver's powers are impossible. This would only be answerable using in-universe evidence to support or refute the claim that Quicksliver experiences an altered sense of temperature while travelling at high speed.
Comment: @ApproachingDarknessFish I don't think this relates directly to the work.  It does not ask for a clarification of an occurrence within the work, or a seminal idea integral to the work.  Rather, it talks about a hypothetical situation that is not present within the work itself, and that the work does not touch on.  The work provides the topic for the hypothetical, but the relationship between the work and the question is not direct.
Comment: @ApproachingDarknessFish This would suppose that every other part of the in-universe physics behaves exactly the same as the real-world, enabling us to answer based off of what we know IRL.
Comment: I did try to apply real world physics to quicksilver but it doesn't work. Even if his body is perfectly accustomed to the insane momentum changes, the momentum due to him arranging guards' arms in the kitchen scene is not conserved. So don't :) And vibrations do not change due to speedy objects.
Answer: You are thinking about this all wrong
When Quicksilver runs, he tastes what they were cooking, not because he is slowing down the air around him, but because his senses are sped-up. Quicksilver can both move and think faster than a standard human being... which is honestly something he would need to be able to avoid death-by-obstacle while running at such high speeds.
Also, when any object moves, it displaces air. Move fast enough, and you will compress a layer of air in-front of yourself, which increases its density, which creates drag and heating and is why people used to think it was impossible to break the sound barrier. It is also why a baseball traveling at 90% C (C is the speed of light) would create a fusion bomb that would vaporize a city. While Quicksilver seems to ignore the effects of this through unstated reasons (possibly just brute-force), the compressed-air layer still contains whatever it had in it. That would concentrate the scent of what was being cooked in the kitchen, making it more noticeable.
So, it is not that Quicksilver cools down the rest of the universe when he is moving (quite the opposite, in-fact). It is, frankly, mostly almost entirely due to Quicksilver's far-enhanced senses and a tiny-bit due to air compression effects at Mach speed (not to be confused with Mach Effects, which are related to Relativity) that he can smell what they are cooking in the kitchen.
Comment: Ohh okay, that actually makes more sense, thank you for answering.


May I ask database modeling questions that have to do with accounting problems?

Question: The reason I ask is that I asked a database modeling question that was also an accounting question, and it got closed.
Comment: FYI I reopened that Q for you after the edit.  In the future, feel free to flag it for moderator attention with a custom message about reopening after you clean it up and we will catch it quicker.
Answer: Before we begin, just a note. You might want to read: Should 'Hi', 'thanks', taglines, and salutations be removed from posts? We tend to discourage all this "hi, how are you ... thanks for reading my question ... hope you can help .. " etc. It's even a bummer when you mention Neil
A long-time stackexchange supporter with 7000+ system-wide rep
The question, as current, reads:
Let's say you're a car dealer, selling cars.

When a customer buys a new car, he often trades in his existing car.

Just wondering if it's:

A) a deal with a sales order for the new car , plus a purchase order for the trade in

B) a sales order for the car, with an adjustment for the trade-in on that sales order

C) something else?

Thanks!

So let's take this in turns:
Let's say you're a car dealer, selling cars.

When a customer buys a new car, he often trades in his existing car.

Ok, so we've got the setup to a question, much as academics would do for assignments. This sounds wonderful. As a matter of fact, car sales are a commonly academically considered question, because they do tend to be highly specialized. There's dealers lots, commissions, manufacturers, vins, makes and models, it's all highly complex, so this is good.
Then you get to:
Just wondering if it's:

A) a deal with a sales order for the new car , plus a purchase order for the trade in

B) a sales order for the car, with an adjustment for the trade-in on that sales order

C) something else?

Thanks!

And this is where we have a problem with the question, which makes it vague. It sounds like you're asking us to help you define the business domain, and not a database design. So let's see if we can focus this down from domain design to database questions:
To start with, you're trying to decide which of two database models seems like it would work best, which is again a business domain issue (we don't know how your data is best represented, because we don't know what your processes are). But we can make an assumption about your data, and that is that every trade in must have an accompanying sales order. This doesn't account for new sales, which says that there doesn't have to be a trade in to purchase a car. Therefore, it makes more sense to have those as two separate entities, obviously. So the best thing to do is to represent trade-ins as a line-item adjustment on the car, from a data standpoint.
But, I have a feeling that there's actually a lot more nuances to this, so I'm going to suggest you talk to your business manager who would be most aware of the actual accounting paperwork to suggest how the business model works, and then ask them to help you actualize the data model as relations/models, and then build your tables off of that.
Hope this helps.
Comment: ++ to you! You always do a good job of being gentle and firm in your answer and you try to teach, rather than writing someone off. I appreciate that. Thanks for going the extra mile to make [main] and Meta what they are!
Comment: I try, but I always feel like I'm being overly snarky, so if that came across, then everyone has my apologies and is free to call me out on it. I do want to see this question reworked to be useful, so ... hopefully it will be.
Answer: Of course.  The question that you are referring to was written as a purely accounting question.  As I mentioned in the updated comment:

If I read your question there is no mention of data modeling, design, or databases of any sort. Nor tables, or indexes, or relations. I understand what you are trying to get at but it needs to be clear in the question, and as currently written this could be in an accounting exam.

Bear in mind that part of our goal on the SE network is to make things  clear an easy for future visitors - there is 0 chance that someone will find that question helpful for database modelling since they will never find it unless they are looking for how car dealerships handle accounting for trade ins (with no reference to databases).
Answer: YES, you most certainly may ask database modeling questions that have to do with accounting problems.
Our contention is that you didn't ask one of these.  You asked an accounting question with database modeling implications.  You shouldn't let database design drive the business model.  Determine what is best for the business and then determine how to best implement that in the database.


what does HANDLE(RefCnt) mean in windbg?

Question: The following is my checking gcroot of the object 0330e9a8.
I found Its root is a hanle with its type is "RefCnt".
How could I get the actual reference count of it. And How could I know WHICH object obtained its reference?
<code>0:042> !GCRoot 0330e9a8
Note: Roots found on stacks may be false positives. Run "!help gcroot" for
more info.
Scan Thread 5 OSTHread 534
Scan Thread 8 OSTHread 60c
Scan Thread 9 OSTHread 1120
Scan Thread 10 OSTHread 1b30
Scan Thread 11 OSTHread 52c
Scan Thread 12 OSTHread 1da8
Scan Thread 15 OSTHread 1cbc
Scan Thread 19 OSTHread 1808
Scan Thread 22 OSTHread 1b6c
Scan Thread 23 OSTHread 1e70
Scan Thread 0 OSTHread 1a34
Scan Thread 32 OSTHread 1840
DOMAIN(001C1050):HANDLE(RefCnt):d31460:Root:0330edf8(xxxxxxx)->
0330eedc(xxxxxxxxxxxx)->
0330e9a8(xxxxxxxxxxxxxx)
</code>
Answer: It's a GC handle that keeps .NET objects reachable for unmanaged code.
for example: subscribing to COM object event.
What types of roots would you normally see when running !gcroot and what do they mean?
ESP:    ESP=Extended Stack Pointer, Object is in use on a stack
Strong: Strong reference, Typically a static variable
WeakLn: Weak Long Handle, A weak reference that is tracked through finalization (can be resurrected)
WeakSh: Weak Short Handle, A weak reference, can't be resurrected
Pinned: Pinned object, pinned at a specific address, can't move around during garbage collection.
RefCnt: Reference count, referenced as long as the reference count is > 0.
See: .NET Debugging Demos Lab 7: Memory Leak - Review


How is 'rm -rf /' able to delete all files in the system?

Question: I can't get my head around rm -rf / : after the kernel and /bin is deleted, how does rm maintain a run time stack, and communicate with the file system & hardware till it completes deletion? Is rm statically linked with all needed binaries and load the whole file system directory tree into memory when the command initiates?
Comment: file need by rm (mostly library and rm itself) are not deleted until rm ends. kernel and your bash login are kept in memory.
Comment: @Archemar: Just an assumption or is `rm` really programmed to do so? Is this a real use-case so that someone defines a requirement for this?
Answer: It's due to the way filenames and file data are separate. When you delete a file you're just deleting a named reference (hard link) to the data, not the data itself. When all of the references are gone from the filesystem the kernel will go ahead and free up the data -- but only if no running processes currently have the file open. Until then the file is not really deleted, it's just not available via its filename any more.
Answer: No matter the kernel file is deleted, the kernel will keep working until shutdown, reboot or crash.
Similar happens with the running processes, the most common for ELF executables is all their dependencies (can see the particular corresponding files running ldd $(which rm)) are loaded from the filesystem to the virtual memory system, not freed from memory at least until all instances of that process are done. This is why hot replacement can be done on most executables and libraries.


Datatype - Salesforce to Marketing Cloud

Question: What should Marketing Cloud data extension datatype be for source field coming from Salesforce that is Double, Precision=18, Scale=0.  Marketing Cloud data will be sent back to Salesforce.  Thanks,
Answer: If your source field coming from Salesforce is Double, Precision=18, Scale=0 then in SFMC Data Extension you could use Decimal with size 18,0


New upgraded Ubuntu 18.10 boots to blank screen (nvidia graphics card)

Question: After the upgrade, the system boots to a blank screen. Cntrl+Alt+F1/F2 doesn't do anything ... but the system is running, I can ssh to it, and ALT+PrtScr+B will trigger a reboot.
Doing an SSH the system does start wayland (it is running), but the screen is blank.
Things I tried:

When booting at recovery mode, the screen freezes after a while. I suspect the system is running (since I can do Alt+PrtScr+B to reboot), but something it starts that is not the console is not working -- I can't check since it doesn't start sshd, and I can't login to the machine.
Nvidia driver version is 410. But i just tried the 390 as well.
I tried starting Xorg manually (/usr/bin/Xorg) from my ssh, and it works. I just run /usr/bin/Xorg (root) and then set DISPLAY=:0.0 and gnome-shell and I get a working Xwindows for rooot.
I also tried a newest kernel (4.19-rc8 I think) recommended in another post, but didn't help.

Any suggestions ? Any error messages / files I should be looking at ?
Is there a way to make gdm work with Xorg instead of Xwayland until it works ?
many thanks in advance for any pointers!
ps.: I've seen a bunch of similar questions, but none of the answers seem relevant.
Answer: After some more digging, I found how to force gdm to use only Xorg:

Edit /etc/gdm3/custom.conf
Uncomment line with WaylandEnable=false

Now the system is usable again -- albeit without Xwayland.


Command for displaying a gem's dependencies?

Question: Is there a command that tells you the other gems that a gem depends on?
Also, is there a way to auto install the gem's dependencies?
Answer: The following information was pulled from the rubygems command reference linked below.
http://guides.rubygems.org/command-reference/#gem-dependency
The first command you're asking for is "gem dependency".  Below is the command description.
gem dependency GEMNAME [options]

Options:
-v, --version VERSION            Specify version of gem to dependency
-r, --[no-]reverse-dependencies  Include reverse dependencies in the output
-p, --pipe                       Pipe Format (name --version ver)

Common Options:
    --source URL                 Use URL as the remote source for gems
-h, --help                       Get help on this command
    --config-file FILE           Use this config file instead of default
    --backtrace                  Show stack backtrace on errors
    --debug                      Turn on Ruby debugging

Arguments:
GEMNAME   name of gems to show

Summary:
Show the dependencies of an installed gem

Defaults:
--version '> 0' --no-reverse

The second command you'll need is "gem install". Dependencies get installed automatically.  Read the quote below from the command reference for more detail.

"gem install" will install the named
gem. It will attempt a local
installation (i.e. a .gem file in the
current directory), and if that fails,
it will attempt to download and
install the most recent version of the
gem you want.
If a gem is being installed remotely,
and it depends on other gems that are
not installed, then gem will download
and install those, after you have
confirmed the operation.
Answer: To find out about a locally installed gem:
$ gem dependency /^rails$/
Gem rails-4.0.12
  actionmailer (= 4.0.12)
  actionpack (= 4.0.12)
  activerecord (= 4.0.12)
  activesupport (= 4.0.12)
  bundler (>= 1.3.0, < 2.0)
  railties (= 4.0.12)
  sprockets-rails (~> 2.0)
...

For an arbitrary gem:
$ gem dependency -rv 4.2.7 /^rails$/
Gem rails-4.2.7
  actionmailer (= 4.2.7)
  actionpack (= 4.2.7)
  actionview (= 4.2.7)
  activejob (= 4.2.7)
  activemodel (= 4.2.7)
  activerecord (= 4.2.7)
  activesupport (= 4.2.7)
  bundler (>= 1.3.0, < 2.0)
  railties (= 4.2.7)
  sprockets-rails (>= 0)

-r stands for --remote, -v for --version. I'm running rubygems-3.0.3. Starting with 3.1.0 you have to omit the regex delimiters:
$ gem dependency -rv 4.2.7 ^rails$
...


Wave Dashboards - Values Table lens

Question: I am struggling with the order of how fields are shown in a Values Table within a Dashboard, how can I get them to appear in an order that makes sense to the end user?
Answer: Can you be more specific
For now:
ordering columns is straight forward you drag the column to a position you want in the left sidebar for changing the header value you can change it in saql query. for filtering use filter condition

Wave Dashboards - Values Table lens


What distro for an old HP (Celeron/384MB)

Question: An old HP desktop just came my way for service.  Was running XP, but the install is trashed.  User would like to switch to Linux, but the box it's only a 950mhz Celeron with 384MB RAM.  It does have a decent sized hard drive though (40GB), so something should fit.  I tried OpenSuSE 11.3, but it just goes to a black screen part way through the installer.  What's the fullest featured distro I can squeeze onto this box?
Comment: possible dupe: http://unix.stackexchange.com/questions/5733/distro-lightweight-and-easy-to-install
Answer: The Debian installer is text-based and is included in the *Ubuntu distriubtion as the "Alternate" CD. There are many lightweight distributions available, such as Puppy Linux, Damn Small Linux and Tiny Core.
More mainstream distributions such as Debian, Ubuntu, Linux Mint and Fedora have lightweight "spins" available, which include either XFCE, LXDE or Fluxbox. Coincidentally I was testing out Lubuntu today (an "unofficial" Ubuntu variant which uses LXDE) and Linux Mint Fluxbox.
It is also worth remembering that the applications which are installed with the distribution or which you install should also be lightweight if possible. It would be counter-productive to install a lightweight distribution on your hardware and then expect it to run Firefox with two dozen tabs open as well as OpenOffice.
Answer: I'd have a look at Archlinux for 686, you could install enlightenment 16 or 17, fluxbox or LXDE as a lightweight windows manager and it should run OK on that configuration.
If you can squeeze some more RAM in it it will help greatly, 1Go would be great IMHO.
Comment: If I had another stick of 256MB PC133 (but I don't) I could get it up to 512MB, but that's about as far as this thing will go.
Answer: I'd try Slackware.  I've put Slackware 13.1 on a very used laptop and had it work pretty well, but I've also backed off to Slackware 11.0 on a circa 2002 Compaq "EVO".  The "EVO" has that ugly, ill-supported "Brookdale" graphics chipset, and the latest and greatest X11 doesn't do Brookdale hardly at all.
Answer: Your question reminded me of a distro chooser mentioned in chat a few weeks back. Seems accurate enough, based on a small and completely unscientific trial I ran with friends.
Anyways, according to that widget, you might want to take another crack at OpenSuSE. Of course, I had to guess on some of the questions; your results may differ.
Comment: Same results apparently.  It said OpenSuSE or Fedora...
Answer: you can also try Ubuntu LTS 10.04 for this box :)
I have heard about the Fedora 14 LXDE/xfce Spins they are good for low power cpu's
Answer: I would say that something with XFCE will probably be your best bet. I had great success with a custom Debian install running XFCE instead of Gnome on a Pentium3 500MHz with 512MB ram; nowadays I would probably use Arch though.
Answer: Well, unfortunately, I ended up giving up.  I did some testing under VirtualBox on my machine and had no problem installing and working with several distros with 256-384MB of RAM, yet I was unable to get any to install on that Celeron.  It's heading out for recycling.  The newer Linux kernels really don't seem to be tolerant of older hardware.  I had to recycle a couple of my own boxes recently as they just wouldn't take newer Linux versions (despite older ones working fine, and having plenty of hardware).  I guess the kernel team must have had to start dumping support for older hardware in order to move forward.  :-(
Comment: Just a further comment.  I grabbed a Pentium 4 machine (that runs Solaris just fine, so I KNOW it's pretty standard hardware!) with 1 GiB RAM and am getting the exact same results.  Are Celeron and Pentium 4 no longer supported by the current Linux kernel?
Comment: Interesting. Have you tried just loading an older distro? Or is that not an option in this case?
Comment: I'm able to load older distros on other boxes with the same symptoms.  Ended up just scrapping this box as the older distro was unacceptable.  Oh well, we tried to keep it going but at some point there's just no helping it anymore I guess.


Free, easy to learn D&D-like game.

Question: What is the best way to share a free role playing game? I've painstakingly worked to make it easy to understand and play. I'm giving it away to get my works out in the gaming world.
Comment: Hello, welcome to StackExchange. It looks like you're new, and we hope you enjoy your time here. One of the things I've noticed with your question is that it seems to be too broad for the purposes of the site. You might want to consider revising it to try to narrow it down a little.
Answer: You might want to try 1km1kt.net, DriveThruRPG, and RPG.net (and the forums for 1km1kt and RPG.net in particular) as potential places to distribute and/or spread the word about your game and get it out there.

Free, easy to learn D&D-like game.


Statistically difference between Normal Multithreading and Executors with multithreading

Question: Can anybody suggest me how can can I show Statistically difference between Normal
Multithreading and Executors with multithreading in-terms of as e.g  CPU time,Total thread
user time,memory usage, & so on
Any suggestions will be helpful.
Answer: I am not sure I understand the term "Statistically difference". I believe that you are asking about using of executors and plain thread API and what is the difference among them.
First, executors a based on threads; it is just yet another layer on top of them. No magic. Plain threading API allows you creation and managing of multithreaded applications but requires dealing with gory details of thread synchronization, pooling, transfering data between threads etc.
Executors framework solves some of these problems. You can define thread pool policy, choose queue type according to your needs and just put new tasks to the incoming queue. The thread pool will execute the tasks according to it configuration.
Comment: Statistically difference means if we have normal multithreading program and same program using Excutor with threadpools , if we execute both programs there should be some difference between them , how can I show it statistically as POC(proof of concept)?
Comment: @PravinG You are better off showing it by reading the code and seeing that fundamentally the same key classes are used.  Using stats may show they are the same in one use case on one platform, but what happens if you do something different?  Only reading the code will show you its the same in all cases.
Answer: The problem is that what your question is asking something that makes little sense.
Before you can meaningfully talk about the "statistical difference" between things, you have to have some way of quantifying and measuring them.  And before that can happen, you have a clear statement of what you are trying to quantify / measure.
What you are asking satisfies none of these criteria.

Assuming that you have a meaningful question ...
At a practical level, the normal way that people try to quantify the effect of something like this (using thread pools versus creating new threads) is to develop a benchmark application with variants corresponding to the two strategies.  Then measure the relative performance.  But this has many problems.
The most fundamental problem that what you are actually measuring is effect of the two strategies for that benchmark, and that benchmark only.  Generalizing from the benchmark to other applications is very difficult.  The problem is that there are "hidden parameters" embedded in the design of any benchmark.  For instance, the number of processors, the number of threads, the length and complexity of the tasks, and so on.  Without having a good intuition as to what the parameters are, it is difficult to design a benchmark to take them into account.  And even if you succeed in figuring out what the hidden parameters are and quantifying their effect, you have the problem that you can't figure out what those parameters will be in a real (more complex) application.  At the end of the day, you'll end up with a model that can't give you quantitative answers for real problems.  (Computing has nothing like Newton's Law of Gravity.)


Getting a table to redraw

Question: I have a view which is a big table. This table is populated from my array of data. This is all working well. The table drawing perfect.
I pop up another small overlay view where you can set some filters. The filter does its thing and the array of data that gets changed and the array changes in size so that there is more or less items to draw in the table.
When the filter overlay view disappears there is no change to the view with the big table.
So I am guessing I need to call something to update the table or get it to redraw. Is there some kinda of delegate method for this or whats the best way to get a table to completely refresh itself?
Thanks
-Code
Answer: UITableView:
<code>- (void)reloadData
</code>
Answer: to reload table data use
<code>[self.tableView reloadData]
</code>
Answer: <code>[tableView reloadData];
</code>
should be called after you modify the data array, to redisplay the data.
Answer: make a IBOutlet UItable *table1 and assign it to your table
then use
[table1 reloadData];

Getting a table to redraw


Chandrayaan landing ellipse size and rationale

Question: From what I hear about the Chandrayaan-2 failure analysis, the spacecraft overshot its landing ellipse and, while struggling to backtrack, crashed. I have been wondering why they had specified a specific patch for landing. I found a couple of articles about site selection, this seems to be the best one. Based on engineering and science constraints for a south pole landing, they picked a landing rectangle 32 x 11 km. On the other hand, the Hindustan Times wrote "The Chandrayaan-2 lander was to land within a 500mx500m area. That meant the lander had no flexibility . In the case of Chandrayaan-3 the landing area has been increased to 4km x 2.5 km."  500x500 m seems awfully tight, even 4x2.5 km. Do you have any insight into why they picked such tight landing specs?
Answer: While I don't know why they chose such tight landing target but we know that while the landing box for Chandrayaan-2 Vikram lander was 500×500 meters the exact spot they were aiming for was even tighter at almost 60×60 meters! Tracing this location helped locate Vikram's debris eventually.
The source of that Hindustan Times report is this lecture and this interview by ISRO Chairman S Somanath.
Chandrayaan-2 lander didn't overshoot the target it just fell short by about 500 meters.
One reason to have such precise landing target could be that they eventually want to land at polar regions where near constant solar illumination is available. And indeed they have a future mission called LUPEX in collaboration with JAXA that will target such landing site and ISRO is supposed to provide lander for it.
Here are few papers on rationale behind Chandrayaan-3 landing site.
Comment: It did overshoot, sort of.  The problem started when the fuel valve stayed open wider than it was supposed to right before the probe entered its "camera coast" phase where it couldn't make any changes to its orientation and throttle.  When it exited that phase,  it was too high (overshooting) and rotated into a head-down orientation to try to get back to its landing track, which it then couldn't recover from because of the rotation rate limits they'd imposed. It did end up short, but it got there because it was initially overshooting.
Comment: @DarthPseudonym During second phase of descent, the reduction in velocity was more than planned due to higher thrust from engines. Being high doesn't mean it was overshooting the target.
Comment: I may be mistaken but my understanding of the situation was that the position they were in during the camera coast was reducing their vertical velocity more than their horizontal, which due to the overperformance was making the target point push out long.


Is there a person class in ImageNet? Are there any classes related to humans?

Question: If I look at one of the many sources for the Imagenet classes on the Internet I cannot find a single class related to human beings (and no, harvestman is not someone who harvests, but it's what I knew as a daddy longlegs, a kind of spider :-). How is that possible? I would have at least expected a person class, and even something more specific such as man, woman, toddler, etc. Nothing of the sort. Why? Did Fei-Fei Li and her team make a conscious choice not to have people images in the database? Am I looking at the wrong file? For the sake of the question, we can consider the ImageNet versions from 2014 onwards.
Answer: You can also take a look at here for the labels in the imagenet. I guess you are right, there is no label for human in the data-set but there is something to notice. There are labels in imagenet like cowboy or some specific hats and other related things to human like shirt and t-shirt. You can take a look at here and also here. In the latter link Yosinski et al, has tried to show that the popular AlexNet has learned to recognize human faces although there is no label as human face in the imagenet data-set. In their paper, they have investigated that Convolutional neural networks may try to learn things that are distributed among layers or maybe not and they may not have special label in the training data. As an example, the face of cats and humans can be referred to. Moreover, as you can see here maybe the aim was attribute learning in large-scale datasets, as quoted in the last line of the page, as the reference.
Comment: I think *learning* for neural networks has very little to do with the human learning process. See these [hallucinations](https://distill.pub/2017/feature-visualization/). Then again, the same idea that these optimized images should show what Neural Networks have learnt, [is deeply flawed](http://www.inference.vc/high-dimensional-gaussian-distributions-are-soap-bubble/) and based on a misunderstanding of what an high-dimensional probability distribution is. The subject is very delicate: my question was much more elementary.
Comment: I like the answer, but I don't understand your last sentence. What do you mean by attribute learning, how it differs (if it differs) from image classification and how is this related to my question (are there `person` classes in ImageNet)?
Comment: @DeltaIV I meant in the last link that I've provided, there is a reference which in that work, they discuss this issue. What I said was like learning faces, which are not the labels but are needed to understand t-shirts maybe.
Comment: Ok, the NNs learn features which look like faces because they help recognizing (or discerning between) labels. Yes, I kind of expected that. Thanks
Comment: @DeltaIV I guess this is maybe what we call *learning*
Answer: I found the class 7846 (name="n00007846") is for person. To access to class description, read http://image-net.org/download-API. Even better, the following text files contain everything you ever need to understand the classes in ImageNet dataset (class = WordNet ID):

http://image-net.org/archive/words.txt maps between WordNet ID and words for all synsets
http://image-net.org/archive/gloss.txt : maps between WordNet ID and glosses for all synsets

n00007846 maps to person, individual, someone, somebody, mortal, soul. The corresponding gloss is: a human being; "there was too much for one person to do".
Comment: Could you link to a source? That would be helpful for other users.
Comment: Imagenet models seem to be underperforming on humans of various backgrounds. In my data there are people in running outfits and they mostly identified as rugby balls and volleyballs.
Answer: You can check this out: http://www.image-net.org/about-stats
Person as big categories and subcategories is listed. Also the Total number of images with persons is provided.


Hardware Description Language questions: Stack Overflow or Electrical Engineering Stack Exchange?

Question: I've been learning VHDL and as I get some questions in my head, I wonder where should I put them. So where should VHDL, Verilog and other HDL questions go? Or does it depend on the question?
Comment: @Andy obviously these questions would go there if it gets created
Comment: I'll see it in either place :). Interested to see what others have to say. There are two related proposals on area51: [FPGA](http://area51.stackexchange.com/proposals/20632/programmable-logic-and-fpga-design) and [VLSI](http://area51.stackexchange.com/proposals/7324/vlsi-design-and-verification).
Comment: I doubt that you would get much (usefull) responses on SO for something like this.
Answer: These should go on Electrical Engineering.
As much like a programming language as HDL appears to be, it's a Hardware Description Language.  It's essentially a schematic, represented in code.  It can be likened to an extremely parallel programming language, but the reality is that most people associate programming with procedural and object oriented programming, and HDL is inherently neither procedural or object oriented.
It would be like saying Ladder Logic is a programming language.
Ideally they should be answered on Electrical Engineering, and we should be trying to attract ASIC designers and such to Electrical Engineering.
As much as ASIC design is similar to programming, there is a big difference between an ASIC expert and a Java expert.  The ASIC expert will feel more at home around hardware folk than system programmers, and the Java expert will feel more at home around software folk than hardware designers.
It can be confusing, but I think we need to consider the expert case - where should we encourage the experts and professional in a given topic to go participate.
Comment: +1 just for the "focusing all the experts in one place" bit
Comment: What about LabView? That seems to be a schematic, essentially implementing a parallel programming language.
Comment: @Gabe Labview is similar to matlab and simulink in many ways.  I don't think it's a great fit for either Stack Overflow or Electronics, but you'll find people in both places that can help you out.  Labview is meant to help visualize sensor measurements and control hardware, so it might tend more towards Electronics, or possibly robotics.  I know there are a fair amount of scientists who use it as well.  Unfortunately it's an odd duck.  If we had a test and measurement stackexchange it would go there. NI has made a big push into robotic competitions, so you would find it on robotics.
Answer: Ok I'm going to try and answer this question myself and see what you guys think.
I'd say if it is more on the line of digital design, it belongs to Electrical Engineering. One instance: Is there a more optimized way of making an incrementer than a full adder? This could clearly be answered by a schematic as well as VHDL source code.
If it is more about the semantics or syntax of VHDL, it belongs to Stack Overflow. For instance: Purpose to providing more than one architecture?. This is clearly very VHDL specific and in theory, the example program could have been a regular "non-synthesizable" program designed to not translate into hardware.
There are of course edge cases such as "What's wrong with my full adder VHDL code?". This could be a syntax problem or it could be a logic problem. Either way, I'd recommend that by-default, we post VHDL questions to Electrical Engineering. Though I'd say between SO and Electrical Engineering there are more than enough people who know VHDL to answer the questions.
Answer: I would send it to where you feel you will get better input (you can try one, if you don't get an answer in a reasonable amount of time, let's say a few days, try the other, keeping a link to the first place).
Many questions are closed as off topic in SO, but those are usually way off-topic. If you are asking this question here, then you probably have enough common sense and you won't have a hostile reception in either place. Good luck! :)
Answer: Recently the SO burninated the "electronics" tag (but not the *HDL one).
They can not see any bad in this burnination. It is a nice result for the MSO community.
Minority opinions are handled as usual on the MSO.
For this reason, I believe, already Electrical Engineering is the better choice. It seems that the Java/JavaScript/.NET programmers have a difficulty to understand that programming is a more broad thing, than generating HTML with various script languages.
Comment: Electronics is a meta tag. A more precise tag is fine IMO. We burninate meta tags, with site-meta consultation all the time.
Comment: @JourneymanGeek It does not reason, why it should be removed. Other "meta tags", like  [cheminformatics] or [declarative-programming], could remain. I see no reason, why [electronics] was nit-picked. Of course they can generate false reasons. The true reason was, imho, what I mentioned in the post: now that most of the programmers work on/for the internet, the lesser educated ones tend to believe that not web programming is not programming et al. And the MSO is dominated by them.
Comment: @JourneymanGeek I think also [cheminformatics] would be likely killed if a similar guy finds it. Fortunately, they only very rarely go to any content which is not web programming, and typically they click away on the spot.
Comment: What does *"it"* refer to in *"They can not see any bad in it"*? To the *tag* that wasn't burninated? To the *tag* that *was* burninated? To the *process* of burninating the tag? Something else? Can you make it clearer?
Comment: @P.Mort.-forgotClayShirky_q They can't see any bad in the deletion of the tag, it is a nice result for them.


2004 Durango brake light fuse

Question: Fuse for brake lights blew so I replaced it, tapped the brakes the lights worked. I then started it up tapped the brakes again no lights. Checked the fuse. It was blown again. Also when I tap the brakes my headlights dim a little bit. Any ideas?
Answer: So first check the bulbs, swap them if necessary just to test.
If it still blows then there must be a short somewhere and you have to inspect the wires for chafing and damage - only needs a small hole & connection to blow a fuse...
One that took us a long time to find was a broken seat spring poking into a wire to blow the fuse. Only happened when the owner sat in the seat as it compressed so much: overweight was an understatement.

2004 Durango brake light fuse


How do I put an image as texture on a triangular object?

Question: I am using the cloth simulator to create an a triangular flag. Everythig works fine, but now I have been asked to put a in image on this flag. So I add the image as plane, it creates a rectangular plane, however when changing this to a triangle, it screws the image. I would like just to cut the parts of the image that do not belong to the triangle, without deforming the image.
Answer: Load  your image in a UV/image editor window, set the 3D viewport in a position that views the triangle from the top, go to edit mode, select all vertices, U to Unwrap and choose "project from view". Then, in the UV/image editor window you can Grab, Rotate, scale the UV map to fit exactly the part of the image you want in your flag. At the end of the process you will have to assign this image to the flag material as an image texture.
Answer: You have to use the UV/image editor to do that.
Image as plane loads the image, creates a rectangular shape and defines the UV map of this plane.
The UV map is the correspondence between the 3D view object vertices and the same vertices projected on an image (or texture).
So, first open a new view, set it to 'UV/Image editor' (1) and choose your flag image in it:

Now if not already done, make your flag look as a triangle in the 3D View in edit mode, select all the vertices in the 3D View, then (still in edit mode), move the vertices in the UV map view to adjust their positions as you want:
Answer: All I did was texture the triangular flag and instead of using UV mapping, selected Generate.  Scaled it to suit with the sliders in the Mapping tab.  The texturing wasn't shown in the gif from your bent pole question because it sent the gif to 9 MB !
The flag -

If when scaling, bits of the repeat images appear near the edges, take the image into Gimp and expand the canvas out so there is plenty of vacant space (bkd or aplpha layer) around the object pictured.


How do I get growl for windows to use native windows 8/10 notifications?

Question: I'm using gntp-send to send messages to a growl for windows instance. GFW hasn't been maintained a while so there dosen't seem to be support for windows 10 style notifications. How would I get GFW to work with the new style notifications?
Answer: Here's an alternative implementation along the same vein of Jonno's one: https://github.com/BobVul/GrowlToToast/blob/master/README.md
The basic principle is the same, but this also sends the original title as sent by the Growl source, and supports a 'silent mode' that stops the Windows 10 notification sound.
Installation
See the Installation instructions in the README. This has changed across different versions.
Answer: I had put together a quick display to mimic this, literally just using the SDK and a quick hack up of the Windows 10 Notification system. Unfortunately notifications require a higher version of the .NET framework than Growl uses (Displays are build for 2.0), so it requires a helper exe which simply takes one argument, the description for the notification.
Source and EXE are available here if you wanted to use it or it can help anyone:
https://github.com/Jonno12345/GrowlForWindows10/releases
Quick video of it in action:
Answer: Its terribly hacky and there's three different things I need to pull in.
Firstly I need a way to actually generate the new style notifications. I'm using toaster for this, download and unzip this somewhere appropriate.
Next you need something to glue toaster and growl together - I used scripty for this. Scripty is not really documented - Basically, you can retrieve the information from growl as command.exe variables and I did a lot of poking around with 'echo' to work out what worked.
<code>@echo off
set arg1=%2
shift
shift
shift
set arg2=%~7

C:\Users\geek\AppData\Local\Growl\188.8.131.52\Displays\Scripty\toast\toast.exe -t %arg1% -m "%arg2% " -w
</code>
I've put toast in the scripty folder since it seems appropriate and invoked it with a batch file
Basically it pulls out the title and message contents (title is %2 and message is %10 - which needs the use of the shift command).
This will fire up a windows 10 native notification as needed. You could also add a locally hosted image on the notification but I'll leave that as an exercise to the user. It also seems to fire up a cmd window, which needs to be fixed, but another toaster notification app may do the trick
Comment: I actually made something *slightly* less hacky than this (native display that sends to a "notification" program, unfortunately it seems to only allow .NET2.0 displays and the notification needs 4.5 I believe), although it's by no means production quality, I literally just used the SDK they provide and haven't really even renamed anything ... Can stick the files on my Github if you wanted it though. Made a quick video if you cared ;) http://i.imgur.com/ncrxWzE.gif
Comment: I'd be happy to give it a try. I was ridiculously tired when I threw this together and someone suggested calling toast from a c# app as an alternative. I'm suprised no one's done this. There's at least two options for creating toaster notifications and a few requests. I guess GFW's sorta dead, but I can't really find anything else that lets me send notifications as easily between my linux and windows boxen
Comment: You can call a VBScript from Growl Scripty, and if Wscript.exe is the default script engine, there will be no console window.


Color checker for comparing print to screen output

Question: I want to print a color checker to have a set of colors to compare the output from the printer with what I see on the screen. Does anybody have a standard color checker? I can also google one, but apart from something that looks like a nice set of colors I don't really know what's important here...
Comment: What do you mean, like a Pantone scale?
Comment: I was thinking something like these: https://news.artnet.com/art-world/gerhard-richter-color-charts-turn-50-322319 It would be useful if I want to check a certain color in an image i.e. beige or a red brown and compare it to the color checker too predict the results from the printer.
Comment: what exactly do you want that a Pantone scale can't provide?
Comment: Well I think I'm missing something here (like I said, maybe it's a stupid question)... I work with photos, so I can't take i.e. Pantone 199 out of a color picker. In my opinion a color checker that I have digitally (in Photoshop) but also on print (print sample from the printer) could be useful to check & compare colors before sending the final image to the printer. So that's why I was looking for a good system/color scale/color picker/...
Comment: Unfortunately, my solution will not work for you to compare before sending a document off to a commercial printer.  For that, I think you really need a Pantone swatch kit.
Answer: Given that you're looking for this for Photographic accuracy than what you probably want is to look at the X-Rite product lineup of ColorChecker Targets. You'll then also want to look into theirs or others Monitor and Printer Calibration. This will provide you much more consistent results than attempting to print your own.
ColorChecker Targets:

Printer Calibration:

i1Photo Pro 2 Professional Color Management for Photographers would be a complete kit but you might be better served looking at individual product options. There are also plenty of competitors of varying quality to x-rite.

For more on the subject you may want to visit the Photography Stack Exchange:

Photo.SE: Color Calibration
Photo.SE: ColorChecker
Answer: Looking for the same thing about a year ago, I stumbled across something in my printer that has worked well for me. Try digging into the utilities available with your printer--I found that both the printers in our office have the ability to print out a color sample sheet.  My HP printer can print out a list of CMYK and/or RGB colors:

And the Kyocera printer has a color chart that is actually matched to Pantone colors:
The option to print the page is available in the utilities of my HP printer:

But I had to dig fairly deeply into the information that we received with the Kyocera to find the page there (it was on a thumb drive that they provided us when we first leased the printer).
I would go to the website for your particular printer and do some searching for a color sampler, or something like it, and see if you can find something similar for your particular printer model.
EDITED TO ADD:
By the way, this is a great way to find out what colors are reproduced well on your specific printer.  Our Kyocera is really awful with blues--about 40% of the blue hues look like the same washed out blue jeans color.
Answer: Remember this one? An oldie but a goodie!
For doing simple calibration of your monitor to a printer it works pretty well. For actual colour calibration of your monitors other answers already provided here will give you the best solution.


SharePoint 2013: How can I replace a video in an asset library?

Question: I have a video whose URL has already been distributed, but an edited version of the video now needs to replace the existing one. Is there a way to replace a video in an asset library while maintaining the URL? This can be done in Vimeo, but I can't find a way to do it in SharePoint.
Answer: So long as the video has the same filename, just upload it again to overwrite the existing version. The URL to the video will remain the same in that case.
Comment: I've tried this, and it failed. The library just uploads the new video alongside the old one. I also tried uploading a video with an identical Name value. In that case, SharePoint adds an underscore and a six-character string of upper case characters to the end of the Name field. But it leave the original video in the library.
Comment: This is giving me no problems in site assets or in an assets library. When I drag it in, it sees the same file name an asks me if I want to overwrite. When I use the upload option, I have the overwrite box ticked and it replaces the video.
Comment: I admit, it is strange behavior. I would expect the library to simply prompt me to overwrite or to create a new version based on the file. I'm not sure why it is behaving so strangely. I'll keep digging and report back if I find out more.
Answer: I also had this problem. What worked for me was opening the video library in Explorer, then navigating into the folder with the video's title to find the actual MP4, making sure the filename of the new version was identical, then copying the video in through Explorer.
After some thinking, I got a prompt to Copy and Replace, Copy but don't replace, or Don't Copy, as one would expect with a file transfer. My Explorer window kept freezing up, though I don't know if that's related or if SP was just being weird today.
It did take FOREVER to upload, and seemed to get hung up around 95%, but it did eventually work. I went back to the library and can play the new version of the video and there were no issues. Checked the documents that linked to the video and the link remained the same.


Looking for good Inbox management methodology

Question: I get a couple of hundred emails a day for work.  Many are part of an email conversation that spans several days or even weeks, so I'm loathe to just delete them outright, as I might need them for reference at some point in the near future.  The consequence is that I have thousands of emails in my Inbox alone, most of which is no longer relevant.  I use Thunderbird, so I have some organizing features available to me, but what I really need is a good, overall methodology for email management.  Does anyone have any suggestions?  Thanks!
Comment: Thanks for the quick thoughts.  I wish I could have checked 2 or 3 o the answers; I like the Inbox Zero concept.
Answer: A combination of various interpretations of the "zero inbox" strategy combined with the Get Things Done (GTD) process.

Self-Discipline: Only view your inbox a few times a day - when you start work, shortly before you finish work and a couple of times in between.
Mailfile organization: Have two "special" folders in your mail file: basket and soft-trash. Then have folders work (and maybe private) with various sub-folders for projects / topics.
Process: Whenever you open your inbox, deal with all mails, starting at the top and not finishing until the inbox is zero. Depending on the amount of mail, go over the inbox iteratively until empty.

Possible actions per mail are:

delete immediately to the trash of the mailbox (things you definitely do not need anymore)
move into soft-trash folder (things you might need in the short future)
move into basket folder (things you want to keep)
move into a dedicated folder beneath either work or private folders (things you want to keep and are important enough)

Difference between basket and dedicated folders beneath work
Try to put everything into basket and just use the search feature. But maybe there are certain topics / projects / issues that you want to group together and be able to view in their entirety - so you put them in a appropriately named folder.
Another tip for the basket folder - depending on your mail application - is to use tags for enhanced search features.
What to do with the soft-trash folder
Delete mails from the soft-trash folder regularly, e.g. mails that are older than 3 months. This gives you a certain amount of backlog mails when you find out, that you need that mail that you deleted 2 days ago, b/c you thought you would never need it again...
Comment: Just an FYI- I've been running with this type of setup for the majority of this month, and I love it -- thanks again for the help!
Answer: I really like the Inbox Zero strategy. Of course, it requires some effort, but you cannot expect effortless handling of email, can you?
Answer: Inbox Zero is hands down the best answer, as Manni suggested. After you are done with that check out Getting Things Done: The Art of Stress-Free Productivity (Paperback)
It will help you refine your new found superpowers
To summarize the GTD process:

When processing a bucket, a strict work-flow is followed:

Start at the top.
Deal with one item at a time.
Never put anything back into 'in'.
If an item requires action do one:

Do it (if it takes less than two minutes)
Delegate it
Defer it

If an item does not require action, do one:

File it for reference
Throw it away
Incubate it for possible action later

If it takes under two minutes to do something, it should be done immediately. The two-minute rule is a guideline, encompassing roughly the time it would take to formally defer the action.

See the Wikipedia article for more.
Answer: This is a bit extreme/unorganized but what I sometimes do is (in gMail) "Select All" and then glance through and deselect the important ones and then click 'Archive'. That leaves only the important stuff in the Inbox.
I have a lot more unnecessary email than I realize so this works really well for me.
As always, YMMV.
Answer: I quit organizing my email because I felt like I was screwing it up and letting emails pile up and then I just couldn't find what I was looking for because I didn't know what folder I put it in. For what it's worth, I use Outlook 2003 and I get less than 30 messages per day.
Here's what I do now:

I installed Google Desktop because it will let me search my email better than anything else I can find.
I keep one month of email in my Inbox. After that, I move it to a separate archive.
I do have a few folders I use but they are mainly for automated emails I receive and for emails I often reference. Most of these folders have a rule set up that automatically puts the email in that folder and completely bypasses my Inbox.

Good luck!


Pulling Fiber Optic Cable

Question: Someone who has a lot of experience with fiber optic cable told me that somehow the cable needs to be pushed through conduits rather than pulled like I would with a Cat 6. Is this true? If so, what is the best way to push the cable through?
Answer: It's less of an issue with multimode or large bundles of fibres but yes, for single mode fibres it can make a lot of sense to 'blow not suck', the way it's usually done is to attach the end/s of the fibres to some form of baffle that almost completely blocks the air on all sides of the conduit and then it's simply blown up the conduit. Think of it a bit like a blow-pipe.
Comment: If I buy just a simple 100m pre-terminated fiber cable, wrapped the LC connector with something to protect it and then pushed it with a cable snake, do you think that would work OK? I'm pretty certain my conduit has a hole in it, so I'm not sure I can blow something through. Thanks!
Comment: Reckon you'd be fine but buy a spare cable just in case.
Comment: I always used a plastic grocery bag and a shop vac.
Answer: Push Pull control cables are the most reliable means of transferring motion. They are available in various mounting configurations, travel or stroke length, overall length and temperature options.
3 Series Push-Pull (Rods 10-32 or M5-0.8)
4 Series Push-Pull (Rods 1/4-28 or M6-1.0)
6 Series Push-Pull (Rods 5/16-24 or M8-1.25)
8 Series Push-Pull (Rods 3/8-24 or M10-1.5)
If further assistance is required let me know.

Pulling Fiber Optic Cable


Size of Mean Squared Error (MSE)

Question: Is there a rule or a scale for judging if a certain MSE is small, very small, big or very big? Please give also a source to underpin your recommendation.
Answer: There is no such rule and there will never be one. MSE, like many other similar criteria is a relative measure (like many other things in statistics, say correlation, or size of confidence intervals). It uses the same units (squared) as your data.
To simplify the example, let's say that we are talking about mean absolute error. Imagine that your variable is distance in meters, you have some model that outputs predictions that on average differ by thousands of meters -- is MAE big or small? Now imagine that you recoded your data into kilometers, now MAE is just few kilometers -- is is "smaller"? It is the same with MSE, but the units are squared.
You can check also the thread that discusses similar case of interpreting the size of standard deviation.

Size of Mean Squared Error (MSE)


Error creating a Linux image/VM for upload to Azure due to incorrect correct size

Question: I saw a similar thread on this, but doing the exact steps in that thread, does not work for me. I want to upload a Linux image (which is qcow2) after converting to VHD image, to Azure.
I converted the qcow2 image to raw:
qemu-img convert -f qcow2 -O raw myimage.qcow2 myimage.img

Next, my raw image is an exact multiple of 1M, so I don't need to resize it.
ls -l myimage.img
-rw-r--r-- 1 user1 user11 2313158656 Mar  5 00:18 myimage.img

<2313158656 is exact multiple of 1M>
Then I converted the raw to VHD on a Ubuntu VM which has qemu 2.6.1 installed, using the force option:
qemu-img convert -f raw -o subformat=fixed,force_size -O vpc myimage.img myimage.vhd

Now, the qemu-img seems to have added 512 bytes to the image, hence I still can't upload in Azure.
ls -l myimage.vhd
-rw-r--r-- 1 user1 user1 2313159168 Mar  5 00:39 myimage.vhd

Uploading this VM to azure gives this error:

The VHD for disk 'clid01b1a17d9ec0eb1-os-1488675181694' with blob https://vmxstorage.blob.core.windows.net/vhddisks/vFPC-20170216.vhd has an unsupported virtual size of 2206.4765625 MB. The size must be a whole number in (MBs).

How do I create a VM with the correct size of multiple of an MB?
Thanks
Anjali
Answer: Try rounding instead:
rawdisk="MyLinuxVM.raw"
vhddisk="MyLinuxVM.vhd"

MB=$((1024*1024))
size=$(qemu-img info -f raw --output json "$rawdisk" | \
       gawk 'match($0, /"virtual-size": ([0-9]+),/, val) {print val[1]}')

rounded_size=$((($size/$MB + 1)*$MB))
echo "Rounded Size = $rounded_size"

Resize to $rounded_size
qemu-img resize MyLinuxVM.raw $rounded_size

And finally convert
qemu-img convert -f raw -o subformat=fixed,force_size -O vpc MyLinuxVM.raw MyLinuxVM.vhd

Reference:
Information for Non-Endorsed Distributions


How can I set a display resolution of 1366x768 in a Acer Aspire One ZG5?

Question: How can I set a display resolution of 1366x768 in a Acer Aspire One ZG5 within Ubuntu 12.04? The only resolutions available are 1280x768 and 800x600.
Comment: Perhaps this can be solved by setting some sort of overscan effect?
The annoying part of this resolution is that even some of the simple setup windows in Ubuntu, are to big for this resolution. The bottom half is outside the screen and can't be reached with the mouse. Therefore it takes guesswork to tab down to the Apply or Okay button.
Answer: Answer: It is not possible to set the display resolution to 1366x768 in a Acer Aspire One ZG5.  The Acer Aspire One ZG5 does not support resolutions higher than 1024x600.
As you have 1280x768 listed under System Settings > Displays, it is very likely you do not have an Acer Apsire One ZG5.  Ubuntu 12.04 will correctly detect the display's native resolutions and populate the settings appropriately during installation.
Source: http://support.acer.com/acerpanam/netbook/0000/Acer/AspireOneAOA150/AspireOneAOA150sp2.shtml
Answer: I believe what he is talking about is DOWNSCALING on the ZG5.
There is a program for windows that downscales 1024x768 on a realtime 1024x600 display.
It is called a1ctl.
The result is that the picture is not that good.  The upside is that you can see the entire normal screen which is important for some programs and some games.  That is why a downscaling program for ubuntu, any flavor of ubuntu, linux is so important.
In the future I may be working with small tft screens with omap processors for robotics.  If UBUNTU has downscaling I would rather go with them rather than creating custom installations of Gentoo!!!
Answer: Click on the cog in the top right hand corner and select Displays.  Then the Resolution drop down should include the valid resolutions.
Comment: Are you sure the screen supports that resolution?
Comment: I only have two options: 1024x768 (4:3) and 800x600 (4:3). The question is How can I add additional resolutions?


ios8 webview with webgl = smooth scrolling in web apps?

Question: I was at an html5 meetup recently, and heard another attendee say that ios8 webview has webgl and as a result, web apps (with phonegap) will finally have smooth scrolling. From googling around, it seems that webgl is a graphics library usually used for 3d stuff. Is that correct? If so, how would it have any effect on scrolling?
Answer: webgl is a hardware accelerated low level API for the HTML canvas element that allows drawing of 3D and 2D graphics. It doesn't have any direct effect on the scrolling of web pages. However most scrolling effects involve a lot of elements being animated on the page based on scroll events. There could be performance gains by throwing some of this content onto a hardware accelerated webgl context, rather than the DOM. This would avoid layout calculations and other performance overhead. However, this can add another level of complexity to the web application. Of course this would all depend on the content (what is taking place while a user scrolls) and the performance of webGL on the device.


Smoke Effect Colors Overly Dark and Gray When Rendering with Cycles or Eevee in Blender 2.92

Question: I tried to make a multi colored smoke effect because it looks cool. Unfortunately, this feature only seems to work with Workbench Render Engine while in wireframe view. Indeed, once I try to render with Cycles or Eevee, smoke is dark and gray. I tried to type "color" as some have recommended, but this doesn't seem to help. Here's the blend file in case you're asking: https://we.tl/t-DW0AlOQdOX
Answer: The color is there, you just needed some more light. :)
Also, the colors are multiplied by the color input of the Principled Volume node.
Answer: Before anything else, here is an absolutely free YouTube video course on MantaFlow, which should give you everything you could possibly need. Here's the link: ( https://www.youtube.com/playlist?list=PLgO2ChD7acqElskP1q7SQKWgOybrO54Xv )
MantaFlow is still a bit finnicky, especially since recent updates changed its baking options. As such, you have to make certain you set up a few things before you begin your MantaFlow simulation.
1: It may sound silly, but: don't forget to add a light to your scene, before beginning your simulation.
Allow me to show you something you've probably shrugged off as a bug.

This is a picture of what a MantaFlow sim startup is supposed to look like.

and this is a picture of a MantaFlow sim startup when you forget to place a light in your scene (this is all in Solid Mode).

(delete everything, reset smoke sim without a light:)

Unfortunately, MantaFlow shaders in Solid Mode are not treated the same as Blender's built-in viewport mesh-shaders, which are automatically lit, regardless of the light from your scene. So you need to add a light source, otherwise your simulation will be dark, or rather, unlit.
Onto the next point, which I think will help fix your issue.
Let's take a look at Principled Volume Shaders. A Principled Volume Shader will allow you to easily color and light your volumes with a few simple clicks and swishes!
Your smoke domain comes with a Principled Volume Shader if you used Quick Effects > Smoke. You can access it from the shader tab by selecting the bounding box of your smoke domain.

Let's keep it simple, and answer the question above: how can we turn this smoke blue?
With your domain selected, you can change your volume's color using the "color" setting from your principled volume shader!

And we're done!
I hope that this helps! You're awesome, my friend -
And keep the smoking to Blender!
<3


how we can set file pointer new position in terms of lines in c

Question: As i think we have fseek function to set file pointer's new position measured in terms of bytes. How we can move file pointer new position in terms of lines?
Answer: The short answer: there's no easy way.  A file in C is a bunch of bytes, and there is nothing in particular that makes the bytes '\n' and '\r' special (depending on your system).  If you really care about a general solution, I would recommend building a lookup table for the byte offsets of line endings as you read the file, and then using it to jump around in the file later on.
Answer: Cant make pointer directly to the lines . Reads the file
Answer: The basic stdio functions operate on bytes only. You will have to read the file byte by byte and count the lines yourself.
Answer: I was facing the same problem. My solution was to store the seek positions of some of the lines and doing a forward search from there.
Eg. If you have a million lines, you can store seek positions of every thousandth line.