UBUNTU Windows Common Storage

Question: I bought myself a new laptop with 1 TB hard-disk.While installing Ubuntu i made that Windows 10 stays in a 200 GB partition.I thought i could create a partition  for Ubuntu while installing but i couldn't.So now i have 200 GB for Windows and 800GB for Ubuntu. I would like to leave 100 GB for Ubuntu and have 700 GB common storage to access from both storage.So any idea how i can do it?
I kinda new to Ubuntu and I would like to have your help?
Thanks!**
Comment: You may use _gparted_ to shrink the Ubuntu partition then access the extra space accordingly.
Comment: Give Windows the larger partition. When logged into Ubuntu you can mount the NTFS filesystem. The Windows partition (NTFS) could not see the Ubuntu system, but the Ubuntu system could see the Windows partition (NTFS). You may need to run gparted from a Ubuntu on USB to shrink the size of your Ubuntu partition. Then you should be able to adjust your Win 10 partition to the size you need.
Answer: Log in to Ubuntu and install Gparted
you can find it in the software center or install it via terminal:
<code>sudo apt install gparted
</code>
after installing you can run gparted and resize the partition of ubuntu to the size you want it to have. This should work without a problem on a fresh install since the overall partition usage should be way below 100GB.
After the Resizing of the Ubuntu Partition you should be able to use gparted or windows to create a NTFS partition that you can then use/mount in Ubuntu too.

UBUNTU Windows Common Storage


Worthwhile to use Three Sacred Treasures when replaying Chapters 9 or 23?

Question: After clearing chapters 9 and 23, where Pit equips himself with the Three Sacred Treasures (Light Arrows, Pegasus Wings, Mirror Shield), for the first time, you have the option to play through the stages without using the treasures. Is it worth using your own weapon to play these stages, or would it be wiser to stick with the Treasures?
Answer: To start, let's look at the benefits of using the Three Sacred Treasures:

Relatively high damage output
Extremely rapid continuous fire with auto-targeting ability and decent range
Large charge shots with average charge time, high homing, and long range
Only weapon capable of damaging/destroying Ornes (those floating death-touch skulls)!!
Mirror Shield can block some flanking attacks

These points make the Treasures a great choice for playing through either chapter on lower Intensity levels. However, based on your unique play style, you may prefer your own weapon to the Treasures, which are exclusively a bow-type weapon. Plus, in my experience, enemies become much more resilient above Intensity 5.0, causing the Treasures to quickly lose their effectiveness. In these cases, it'd be wiser to take the weapon you find most comfortable instead.
Here's how you can make up for the absence of the benefits reaped by using the Three Sacred Treasures:

Plenty of weapons with value of 260 or higher have enough attack power or special effects to overshadow the strengths of the Light Arrows; pick one that you can use easily, learn how to make the most of its attributes and attack types, and select Powers that either make up for the weapon's weaknesses or add to its strengths.
In most cases, Ornes are easy to spot and avoid; if you don't have the Light Arrows to slay them, memorize their appearances and motion patterns in Air Battle and use quick movements and dodges on land to avoid an instant death.
Instead of relying on the Mirror Shield to guard your blind spot, learn the placement of enemies and study their telegraphs and attack patterns to know how and when to effectively dodge a frantic assault. Also, don't forget that the direction(s) of incoming attacks are shown by an orange-yellow indicator on the edge of the top screen; use these indicators and the sounds of enemy attacks to gauge the right moment to dodge and keep a sneak attack from getting the better of you.

Lastly, let's take a separate look at the two chapters where the Treasures are usable:
Chapter 9: This stage is one huge endurance test; the Air Battle is hectic and chock-full of dangerous enemies, including a fairly tough mini-boss, and the land segment is very lengthy, starting with re-appearances of three previous bosses and leading into a long and twisted trek through Medusa's stronghold. If you don't have a reliable weapon, or you don't have confidence in your survival skills, it might be best to stick with the Three Sacred Treasures.
Chapter 23: SPOILER ALERT!! This explanation gives away a bit of the late-game story, so don't read until you've beaten this stage once and actually have the option to not use the Treasures.

 If you take the Three Sacred Treasures with you in this stage, remember that Hades will destroy them near the end of the Air Battle segment, rendering them useless and forcing you to use whichever weapon you had equipped previously for the remainder of the chapter. The sheer number of enemies in the Air Battle might make the Treasures out to be a good option (again, auto-targeting is VERY useful), but with the right weapon, memorization of enemy appearances, and some practice at dodging in flight, they really aren't necessary at any Intensity level.

In the end, it all comes down to how you play the game, but you might take some of the above factors into account when deciding how to go about replaying these two chapters.
Comment: The three sacred treasures start feeling really weak at higher difficulties. Players trying to beat either chapter on 7.0 or higher should definitely bring their own weapon.


"Object based Image Segmentation" and some options are absent in SAGA

Question: Although I have the latest version of SAGA, "Object based Image Segmentation" and some options do not appear when I click on "Geoprocessing>Imagery> Segmentation>? " Why are they absent?
Answer: I have the same issue. I tried the zip file installation and the exe file, no success.
Finally, I clicked on Geoprocessing > Load Tool Library > I went in modules, toolchains and I selected "obia" xml file. And it worked! Now I have the obia option in imagery/segmentation.
If you're not familiar with SAGA (like myself) this may be the solution to your problem with absent tools.
Answer: I figured out that If you installed and use SAGA from the downloaded file named "setup.exe"(That was what I did), some options don't appear at the menu.
Therefore it seems better to use the software from the zipped file. Now all options are seen.


How to block Skype using Squid?

Question: Is there a way to block Skype using Squid?
Answer: Blocking Skyep in squid is a two stage process, firstly Skype by default uses an outbound connction on a port in the range of 2940-3000, so these should be blocked on your egress filtering.
However, if skype cannot connect on these ports, it will try to connect using port 443, which you obviously cannot block without preventing SSL access to any sites. However, Skype uses a connect method called 'Connect' to make this connection, so this can be blocked by creating an access list that looks for connections to an IP address, using the 'Connect' method:
<code># Your acl definitions
acl numeric_IPs urlpath_regex ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+
acl connect method CONNECT
# Apply your acls
http_access deny connect numeric_IPs all
</code>
Take a look at this article for more information.
Answer: You may want to read network-admin-guide-version2.2.pdf for relevant information. There's also a document which details how Skype gets around firewall and proxy restrictions but I don't have the URL for it.
Answer: File you say can be found here: http://download.skype.com/share/security/network-admin-guide-version2.2.pdf this maybe can help as you say...

How to block Skype using Squid?


Batch Dissolve Polygons based on Attributes in QGIS or FWTools

Question: I was wondering if anyone can help with batching a dissolve.  I have a few hundred polygon shapefiles that I want to dissolve based on an attribute.  I would like to do this in QGIS or FWTools.
Answer: fTools is a python plugin for QGIS that can do it and you could hack it into fitting your needs.
An easier alternative is the QGIS GRASS plugin, which includes v.dissolve, but then you're easier off scripting with GRASS directly. If you're not familiar with PostGIS, this may be a faster approach.
Answer: Maybe load them in postgis and write a small script to do the dissolve.


Connectify network for android

Question: I have a wired internet access on my win xp laptop. And want to share it to my HTC android smartphone. So, I've installed Connectify Hotspot Pro 3.7.1, created a network, but my android even doesn't see that network. However, another windows based laptop sees it.
Answer: It's because Android can neither connect nor "see" ad-hoc networks. There's supposedly a work around in which you install some third party software on your Android device, but it only works on a small list of phone models. A quick Google search will lead you to the page. Sorry, I'm on my tab right now otherwise I'd link it here.
EDIT:
Found the link to a similar situation: https://stackoverflow.com/questions/5100928/how-to-connect-android-wifi-to-adhoc-wifi

Connectify network for android


Why is the speed of light arbitrarily the limit?

Question: I know Einstein was great and all. Why is it that exactly at the speed of light is where infinite energy is required to accelerate any object with mass? Is it simply because the math of relativity checks out and explains most of everything? Are there any physicists who disagree with Einstein's theory?
Comment: The answer to most "why" questions in physics is: because that's what we observe in nature.
Comment: See [How Galileo could have derived the special theory of relativity](http://www.loreto.unican.es/Carpeta2013/GALILEO-DISCOVER-RELATIVITY_AJP000157.pdf).
Comment: The point is not that speed of light itself is the limit ; it could be another particle it would not matter that much. The point is that there *has* to be a limit (otherwise modern physic would be pretty much messed up to the ground).
Comment: @Max Well, it has to be another *massless* particle. An it has to be sufficiently long ranged that it's speed can be measured and that leaves  ... well, the graviton once (or if) we're ever equipped to detect the fool thing.
Comment: Maybe you should add "speed of light in vacuum". See http://en.wikipedia.org/wiki/Cherenkov_radiation
Answer: For the non-physicists amongst us, Brian Greene gives a non-mathematical but intuitively satisfying explanation in 'The Fabric of the Cosmos': In a loose sense, when we are at rest, we are moving through time at the speed of light. As we start to move through space, what we are actually doing is diverting more and more of that motion to a spatial direction rather than a time direction, but the combined velocity remains constant. Thus we cannot exceed the speed of light, because at that point, we have diverted the entirety of our motion to the space direction.
(I'm paraphrasing, but I believe I've caught the gist)
Comment: Not bad +1. And you're quite right in a precise sense too: the velocity four vector does indeed have a constant "length" of $c$: the four velocity's components are $(c,\,v_x,\,v_y,\,v_z)\,\gamma$ where $\gamma = \sqrt{1-(v/c)^2}^{-1}$. The length of a four vector $x_0,\,x_1,\,x_2,\,x_3$ is $\sqrt{x_0^2-x_1^2-x_2^2-x_3^2}$, so you can explore Brian Greene's explanation a bit with these ideas.
Answer: Let's assume, for argument's sake, that the Galilean transformation holds rather than the Lorentz transformation.
Then your questions would become

Why is infinite speed arbitrarily the limit?  Why is it that exactly
  at infinite speed is where infinite energy is required to accelerate
  any object with mass?

I suspect that you wouldn't, in fact, think of asking such questions since they almost answer themselves.
Moreover, infinite speed would be an invariant speed - a speed that is measured to be the same in all reference frames - since (loosely speaking) $\infty + v = \infty$.
If we ask the question "what if there is a finite invariant speed", the mathematical answer is the Lorentz transformation where $c$ is the finite invariant speed.
Indeed, if we let $c \rightarrow \infty$ in the Lorentz transformation, we recover the Galilean transformation.
From this perspective, the result that accelerating to the invariant speed requires infinite energy and is thus impossible, doesn't seem so odd.
To summarize, without postulating that the speed of light is invariant, one can derive the form of the Lorentz transformations from just the principle of relativity.  In this form, there is an undetermined finite invariant speed.
That light propagates at the invariant speed is then simply an empirical fact rather than a postulate.
Comment: The problem is that the paper you cite assumes v in one ref. frame and −v in the other ref. frame, i.e. v'=-v. However, time dilatation and length (distance) contraction means that the two variables change in inverse proportions, i.e. if t' is larger than t then (absolute) x' is smaller than x. Now, the postulated constancy of the value of the velocity requires that v=x/t and v'=x′/t′=-v, and therefore x/t=-x′/t′. As t is always less than t', then x' must be in direct proportion to t' (in absolute numbers), and therefore larger than x. Which contradicts Lorentz transform equations.
Answer:
Why is it that exactly at the speed of light is where infinite energy
  is required to accelerate any object with mass? Is it simply because
  the math of relativity checks out and explains most of everything?

To say that the math checks out is the wrong way of putting what's going on because it separates the math and the explanation for the math. Einstein had explanations for why he picked the equations he picked. That is, he had an account of what was happening in reality to bring those outcomes about and without that explanation the math wouldn't have any relevance to physics. Einstein's explanation involved ideas about what kinds of measurements are allowed by the laws of physics, see:
http://www.fourmilab.ch/etexts/einstein/specrel/specrel.pdf

Are there any physicists who disagree with Einstein's theory?

General relativity is the best available explanation of gravity and the structure of spacetime. There is a problem with the theory in the sense that it is not a quantum theory of gravity. There is no reason to think that its replacement will involve going back to anything that resembles Newtonian mechanics.
Comment: General Relativity (and a subset of it, Special Relativity) simply _work_, and have coherently explained the world at the macroscopic level. GR (and QM too) don't really offer a deterministic mechanism behind the observed effects (e.g., what exactly _is_ gravity?), so they are unsatisfying in that sense (as well as not yet being unified). If you care to disagree with Dr Einstein's work, you'd better have a theory that explains everything just as well, and then goes beyond GR to explain other things (like QM). There's plenty more left to be done in physics!
Answer: It's not actually. It's not like light has some special status in the Universe. It's just that there is a maximum speed, and light, among other things, tends to get very close to that limit. In practice light is slowed down by its environment, and there was even speculation at one point, that light mad a bit of mass and so neutrinos might move a tiny bit faster. This was retracted, but it goes to show that the thought is possible.
Comment: Light (any EM radiation) moving through a vacuum moves _at_ c, not close to it. Through any non-vacuum, it slows down to c/IR (IR = index of refraction). I've never heard of any speculation that photons had actual rest mass (because it would be infinite mass at _c_.) The jury is still out on neutrinos, although it appears they may have a tiny rest mass.
Comment: So when do we get slow-glass?
Comment: @PhilPerry I believe ThomasAhle may be referring to the retracted "faster than light" neutrinos in Italy, that turned out to be due to a faulty cable.
Comment: @Phil There is no doubt that neutrinos (or at least all but the lightest masses states of...) have mass. The jury reported years ago. We even know a fair amount about the differences of the squares of the masses and there is a limit of the sum of the masses, but that leaves considerable room for uncertainty about the actual values.
Comment: Yes, but I'm really just trying to say that relativity wouldn't fall on light not moving exactly at c, which seems to be the idea Derp is having. We just call the limit 'light speed' because it also happens to be so.
Comment: @PhilPerry: "I've never heard of any speculation that photons had actual rest mass". Here you are: http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html. Although I have my personal reservations, John Baez is a recognized scientist (and apparently very respected here on this forum).
Answer:
Is it simply because the math of relativity checks out and explains most of everything?

Yes, the equations of special relativity have been tested against data innumerable times and have never been falsified.

Are there any physicists who disagree with Einstein's theory?

As far as I know, no.
Comment: Well, I showed you before that this page http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/muon.html presenting the so-called muon experiment actually invalidates SR. Time dilatation and length (distance) contraction means that the two variables change in inverse proportions, i.e. if Δt' is larger than Δt, than Δx' is smaller than Δx (because Δt′=Δtγ and Δx′=Δx/γ). This page claims, however (tables by the 4th and 5th figure) that Δt' is larger than Δt and Δx' is larger than Δx (afaik, what this page shows is accepted by mainstream). There couldn't be a better experimental falsification.


Change user account properties

Question: Creating a couple of new users on an Ubuntu 16.04 I omitted to enter user full name and now I have several users who on the login screen are seen simply as "Comment". System settings doesn't offer the possibility to change this.
How can I fix this? Is it ok to just edit /etc/passwd?
Thanks in advance
H
Answer: I recall I had this problem years back probably on about Ubuntu 14.04 and I installed Users & Groups thinking I would be able to edit the users full name, but found that although you can change every other aspect of the users details you cannot edit the users full name and I found this is simply because the ability for a user to change their own full name is subject to the restrictions in /etc/login.defs. The default configuration is to prevent users from changing their full-name, which makes perfect sense.
To change your own or another user's full name I used the chfn command, this command allows a (normal) user to change all the fields for their own account, subject to the restrictions in /etc/login.defs, or this can be overridden using elevated privileges, by opening a terminal CTR +T while logged in as the user you want to change and running the command:
sudo chfn user
Changing the user information for user
Enter the new value, or press ENTER for the default
    Full Name [user]: New Full Name
where user is the user who is logged in and is the user you want to change the full-name for and New Full Name is the new full name for the user.   You can use the chfn command to change other account details, but you can change mostly all other details via Users & Groups which can be installed via the Ubuntu Software Center.
<code>Usage: chfn [options] [LOGIN]
Options:
  -f, --full-name FULL_NAME     change user's full name
  -h, --home-phone HOME_PHONE   change user's home phone number
  -o, --other OTHER_INFO        change user's other GECOS information
  -r, --room ROOM_NUMBER        change user's room number
  -R, --root CHROOT_DIR         directory to chroot into
  -u, --help                    display this help message and exit
  -w, --work-phone WORK_PHONE   change user's office phone number
      --extrausers              Use the extra users database
</code>
Comment: Dud you had multiple users with the name "Comment" like the OP has? What did you do exactly to fix it? A screenshot or two might be helpful in this situation as well.

Change user account properties


Trying to get sybase db to connect via isql command line.... Gui RazorSQL works

Question: Im using RazorSQL and the settings to connect is
GUI RazorSQL Connections show as
 Driver Class  net.sourcefourge.jtds.jdbc.Driver

 Driver Location  /Java/drivers/jtds/jtds12.jar

 JDBC URL   jdbc:jtds:sybase://IP-address:4100/DATABASE

LINUX connections show
/etc/freetds.conf
[Serverconnection]

    host = 10.10.10.10
    port = 4100
    tds version = 8.0
    dump file = /var/log/freetds.log

/etc/odbc.ini
[Serverconnection]

     Driver          = /usr/local/freetds/lib/libtdsodbc.so
     Description     = Sybase JDBC Server
     Trace           = No
     Server          = 10.10.10.10
     Database        = SYB
     Port            = 4100
     TDS_Version     = 5.0

End goal is to connect to the sybase db Via command line so i can build them in bash scripts but i cant seem to connect to it via ISQL
not sure if theres a driver or jar needed or something really.
Answer: Try changing your odbc.ini file and use Servername=Serverconnection instead of Server=10.10.10.10. This points your odbc.ini file back to your freetds.conf file to get connection info, which is under [Serverconnection]. Whatever is in your freetds.conf need not be repeated in your odbc.ini file.


EEPROM writes/reads wrong bytes

Question: I am using M95512-W M95512-RM95512-DF eeprom for storing my data.
But sometimes it's not storing bytes I want. Instead of it, it's storing successive (wrong)bytes.
Can this occurs because I don't place any wait between two byte writes ?
Answer: I think you need to work at some more detailed unit testing of your software routines that you use to write to the EEPROM. When you do the tests make sure to keep the low level code the same as the failing case to you can keep the scenario close to what happens now.
The simplest test is to use a known data pattern in your test so it is possible to spot patterns in the result that may reveal just what may be going wrong. Try patterns such as:

Data sequence of 0x00, 0xFF, 0x00, 0xFF repeating through a large block.
Data sequence of 0x55, 0xAA, 0x55, 0xAA repeating through a large block.
Data counting sequence of 0x00, 0x01, 0x02 ... 0xFF, 0x00, 0x01 repeating in a block.
Data sequence of two bytes storing the even numbered address address of location as the data.

When you read back the results from these you can tell if bytes are simply missing in the stream, whether extra bytes are sneaking in, some bytes are simply getting wrong values and whether the values that are wrong have any resemblance to the expected value at the wrong location.
You may be having problems in several areas:

You may have a bug in your software driver
There may be signal integrity problems with your handling of the part electrically
You may have coded a protocol error in how you try to talk to the EEPROM

With the specific device that you are using you can write from one byte up to the number of bytes in a "page". When you let the Chip Select pin go high an internally timed 5 msec write cycle happens to place the new data into the array. You either need to delay the 5 msec in your software before the next write is attempted or poll the status register till you see the "Write In Progress" bit clear.
Another thing to consider is that if you are storing multiple byte sequences in one write cycle and are not comprehending "page" boundaries correctly you could be experiencing "roll over" within a page. For example if you were logging a sequential data storage of 7 bytes per write operation to address 0x0000 then 0x0007 etc you would get to the end of the "page" when the write of the next 7 bytes spans across the end of the current page into the beginning of the next page. If you are not accounting for that in your algorithm the bytes that span into the "next page" in fact get written into the beginning part of the "current page". A correct algorithm would need to break up a spanning write into two separate write commands - one to store the last bytes into the current page and the second one to write the remaining bytes into the next page.
Note that the "roll over" problem is a common error in this type of device application.
Comment: Thanks for your answer. Actually I'm writing bytes with separate write commands, not with "pages" and I'm reading Status Register and seeing if "Write In Progress" bit is clear. But still it's not working. I will do tests you suggested me, after that I will write you back for results.
Thanks again
Comment: @ArbnorZeqiri - Depending upon your application the writing of a single byte at a time can cause a severe time penalty by taking 5 msec per byte. Writing a smarter algorithm that accepts records of data to be written at once can save boatloads of time but then you need such algorithm to break up the records into "page" sized chunks and take care if splitting page crossing writes into two.
Comment: One way to avoid the complications of page organized EEPROM devices with their long write times is to look at FRAM devices. These come in I2C and SPI variants. They support true byte write capabilities that are as fast as read cycles. So the software algorithm to talk to them is much simpler for multi byte writes.
Answer: Reading the datasheet of the EEprom you specified says - yes, this can occur because you're not placing any wait.
A write command might be disregarding when a write is still processing.
There are a couple of different problems that could arise - you would need to explain your problem in more deatail...
Comment: I'm just reading Status Register and I'm checking with 0x01, but still it isn't working.

EEPROM writes/reads wrong bytes


Sliding chain over the cassette

Question: Today I have replaced my chain with a kmc z8s. The rear cassette is Shimano acera 8 speed , and is not worn yet , so everything is OK with the cassette. But the problem is that the chain doesn't fit the cassette properly ,when I apply more power on the pedals the  chain starts sliding over the cassette (The lenght of the chain is OK too). What is the solution of this problem ?
Comment: Are you sure you threaded the chain through the rear derailer properly?
Comment: Yes everything is OK . The only problem is the chain
Comment: Does it happen on all of the gears? Are you positive it is an 8 speed chain?
Comment: Is your Acera a Hyperglide (HG) or  an Interglide (IG) cassette? There can be compatibility problems causing jumping if you mix the two and run an HG chain on an IG cassette or vice versa.
Comment: Are you sure you cut the chain to be exactly the same number of links (not the same physical length) as the old one?
Comment: The cassette is Hyperglide , but the chain is not shimano , it is kmc z8s . How to know if they are compatible or no
Answer:
The cassette really is worn.  It takes something of a trained eye to spot a too-worn cassette, and often when you switch to a new chain the cassette will skip worse than it did with the old, worn chain.
The chain is the wrong one for the cassette.  Chain/cassette compatibility is an area where there are no nice general rules -- you have to make sure that the chain you get is compatible with your specific cassette. This includes having the correct speed pairing (e.g. 8-speed chain for 8-speed cassette).
The chain was cut to the wrong length.  A chain is always delivered with 8-10 inches of extra chain.  You must shorten it to the appropriate length, using a "chain breaker".  Some people just wrap the chain around the largest sprockets and eyeball it, but if you haven't developed that skill the best thing to do is to lay old and new chain side-by-side and carefully match up links along the length so that there are the same number of links in the new chain as the old.  (Note that if you just match length the new chain will likely end up a couple of inches too long.)
The chain was threaded through the rear derailer incorrectly.  It's kind of hard to mess up on the front, but the threading through the rear derailer is not intuitive, and it's possible to muck it up.
The derailer is out of adjustment or has been bent somehow.
Answer: it sounds like a derailleur adjustment issue. although HG vs IG compatibility issue could be something to be concerned about. it seems like the tension on the derailleur cable needs to be adjusted, and the stops too possibly. here is an article about how to go about derailleur adjustments.
http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur

Sliding chain over the cassette


Subbasis elements are open?

Question: So the basis elements of a topology are open, and the topology generated by a subbasis is the collection of union of finite intersections of subbasis elements. My question is: Can we claim that subbasis elements are open? Because if we let $U \in \mathcal{T_x}$, then $U = \bigcup({S_{i_1}\cap\ S_{i_2}\cap...\cap \ S_{i_n})}$, then $S_{i_j}\in \mathcal{T_x}$ because the union of finite intersection of $S_{i_j}$ is $U\in \mathcal{T_x}$?
Comment: Well, $S_i$ is a union (of one set) of an intersection (of one set) of elements of the subbasis.
Answer: In your definition of a subbase (or subbasis, but I prefer base and subbase), the set of finite intersections of subbase elements is a base for the topology. And base elements are by definition open (otherwise we'd call it a "network", which is a collection $\mathcal{N}$ of (arbitrary) subsets of $X$ such that we can write any open subset $O$ of $X$ as a union of members of $\mathcal{N}$). Or we could say that base elements are open, because unions of them form all open sets, including the empty union ($\emptyset$) and unions of subfamilies of size $1$ (which are exactly the elements of the base).
A finite intersection of elements of $\mathcal{S}$ is the intersection of a finite subfamily $\mathcal{S}'$ of $\mathcal{S}$. This $\mathcal{S}'$ can consist of one element, so be of the form $\{S\}$ for $ S \in \mathcal{S}$. The intersection is then just $S$, so every element of $\mathcal{S}$ is itself in the set of finite intersections from $\mathcal{S}$. In particular, all $S \in \mathcal{S}$ are in the base so are open.
My definition of a subbase is just "generating set", so $\mathcal{S} \subseteq \mathcal{T}$ is a subbase for the topology $\mathcal{T}$ if the smallest topology that contains $\mathcal{S}$ as a subset equals $\mathcal{T}$. This comes down to the same description as you have (finite intersections form a base) if we adopt the convention that the intersection of the empty subfamily of $\mathcal{S}$ equals $X$ (for which there are good logical arguments, based on the Morgan's laws etc.), so that the finite intersections always form a base for a topology. In this definition $\mathcal{S}$ elements are also open (but then basically (pun intended) by definition).
Answer: Any finite intersection of subbase elements is a base element, therefore, a prebase element is a base element, and any Union of base elements is a topology element, so every single base element is an open set, so a subbase element is an open set.
Answer: Let $\S$ denote the subbase for a topology. Let $\mathbb{B}$ be the basis generated by $\S$.
Let $S$ be a member of $\S$.  If $x\in S$, then $x\in S\cap S \subseteq S$. Note that $S\cap S\in \mathbb{B}$.

Subbasis elements are open?


Differential current sensor probe- Ground leakage current measurement probe for oscilloscope

Question: I would like to know what you use to measure differential current which is also leakage current sensing.
Background: In industry , the AC or DC current flowing from inverter/ converter needs to have low leakage of 6mA / 30mA AC,DC (based on  different standards) , the main current in wires can be 30A. I am searching for current probe which can measure precise 6ma AC/DC from differential pair of wires (Line and Neutral of system / battery + &-ve of system) .
Problem here is regular current probes that measure low current have narrow aperture and differential wire pairs will not fit in the jaw of probe. On other hand the current sensor which have wide jaw do not have sensitivity of 6ma on Measuring noisy lines.
Note: I am searching current probes for oscilloscope
Answer:
On other hand the current sensor which have wide jaw do not have sensitivity of 6ma on Measuring noisy lines...

If you have room to pass, with the wires, 10 times in the sensor, you multiply the sensitivity by 10 times...
One can use then a classical amplifier ...


How do I measure the analogue in voltage of a ICL7136 using an Arduino

Question: I have ICL7136 MQFC (the square one) chip driving an LCD display. it's measuring and displaying temperature data from a thermometer probe. I want to grab the analogue readings an log them with an Arduino as well. How what type of setup would yield something usable. Would I just measure from the IN HI or IN LO to the analogue in of the Arduino?
Comment: This question is more suitable for Arduino SE. It is now in public beta: http://arduino.stackexchange.com/
Answer: It looks to me like the chip has reference voltage pins and then sensor voltage pins.  So it is reading voltage changes from a sensor that reports back in that way, massaging those levels (amplification, scaling, whatever), and then outputting to the display.
Yes, I would think logically reading the same sensor outputs that the chip is reading on IN HI and IN LOW would allow you to access the data.  I am assuming the mere act of connecting to those pins and reading them won't change the voltage, but I would defer on that to those more experienced as I could be wrong.
I think your issue, however, is going to be doing the scaling and amplification and conversion of the signals coming in so that the Arduino and the chip both think a given voltage represents the same (in your case) temperature reading.  Once they both say that particular voltage level is that many degrees then it becomes a data logging issue.
Comment: Thanks for your answer, I think I understand the scaling issues, but I'm still confused on how to hook it up. What am I measuring across? for instance do I connect the Arduino ground to the common ground of the temp circuit? and then the IN HI to an analog in on the Arduino? what does the IN LO represent. pardon my ignorance
Comment: My guess is the chip is designed to work with a number of sensors.  I have a typical 3 wire water sensor in my sump, for example, that has V+, Gnd, and Vout.  The Vout is where the data is.  For my sensor all it does in 0v for dry and supply voltage for wet on the vout pin (digital, 1 or 0).  I would think I connect the sensor output to the IN HI pin on that chip and probably put the IN LO to ground.  With your temp sensor maybe IN LOW is the one to connect and read. But I am guessing so I will shut up.
Answer: I wouldn't directly connect to IN LO and IN HI on the ICL7136 unless you haven't got an input filter - as shown in figure 11 the resistor is 1M ohm and an ADC input on an arduino is likely to upset it.
The other issue is the voltages on the two inputs - normally one could be expected to be 0V but this may not be the case so I'd recommend using an instrumentation amplifier to to take the voltage from the thermometer probe directly.
Somethink like an AD8221 but you'll need to generate the appropriate power supply rails for it - you can probably use the power rail for the arduino but you'll likely need a small negative rail unless of course the offset voltage coming from the probe is greater than 2V above 0V.
Comment: There are a few ICL7136 one for temp, one for humid etc. I'm really just trying to figure out the simplest way to get the data that is going into the LCDs and log it. I does seem like there is a bit of a conditioning circuit before the ICL7136.
Comment: "the resistor is 1M ohm and an ADC input on an arduino is likely to upset it."  That was a piece I didn't know and almost made me not answer the question- whether there was some sort of almost Heisenberg thing going on where the act of hooking up the Arduino to read the input would change the input and make it unreadable.
Comment: @user379468 you need to establish what voltage is on IN LO. If it's at 0volts then no problem - you can wire to your data logger but you may find that one or both systems become noisy. An instro amp saves you debugging noise problems that may come and go and be annoying.
Comment: @mikeY I'm no expert on arduino but a lot of internal ADCs on MCUs require a decently low impedance offered by the voltage source they are measuring or they produce measurement errors and may induce other issues. Heisenburg LOL.


QGIS query editor help

Question: In my QGIS-version (2.18.12, Windows) when opening the expression string builder or the field calculator there is no inline help for the functions. I actually never managed to activate this. Is there an option that I am missing?
Answer: For Query Builder, I never saw an inline help, but for Field Calculator maybe it is shifted until the end as you can see below:

You need to go to the far write of the Field Calculator window until the cursor changes its shape to parallel cursor, then drag the window to the left as explained in the image below
Here is the final shape:

If the above solution did not solve your problem, then try to reinstall your QGIS again.
Comment: It is a duplicate question, sorry. Nonetheless thank you very much for the answer. Best, Christian
Comment: And it actually solved the problem...

QGIS query editor help


What experiment would you perform to establish that the photon has spin 1?

Question: I see that you can use a Stern-Gerlach apparatus for massive particles that can be deflected, but that doesn't work for photons. What would you do instead to measure photon spin in a lab?
Comment: Possible cheap answer: light that went through a horizontal polarizing filter does not pass through a vertical polarizing filter. Then light polarizations that are $\pi/2$ apart in real space are also $\pi/2$ apart in Hilbert space, so the photon is spin 1.
Comment: One can shine light through a medium that turns its polarization and measure the torque on the medium: "Mechanical Detection and Measurement of the Angular Momentum of Light" R. A. Beth, Phys. Rev. 50, 115 (1936). This has later been repeated with different means and higher precision, e.g. with microwaves "A radiation torque experiment", P.J. Allen American Journal of Physics 12/1966; 34(12).
Comment: Theoretically, you just need to show that photon has three *degrees of freedom.* So you need an experiment to show that two of them correspond to *two transverse polarizations* by writing down the *equation of motion* of the photon field while the second experiment needs to show that it is *massless* due to *gauge invariance.* For the first one, any interferometric experiment would suffice while for the second one you need to set very very small upper limits on its rest mass.
Comment: Perhaps the simplest way to determine this at the single-photon level is just to shine resonant polarized light onto some atoms with a known energy structure, and see which transitions are possible.
Comment: Gentlemen, answers go in that other box down there.
Answer: In the case that photons are coherent (having the same wavelength and oscillating in phase), they still separable into two states.
This has to do with the two field components of the photon, the electric dipole moment and the magnetic dipole moment. Dipole moment means that at some time there is an electric field with a plus-minus direction and there is at some time a magnetic field with a south-north direction. Both field components directed perpendicular to each other and both perpendicular to the direction of propagation.
Let's draw the magnetic dipole from down to top as north-south. How many possibilities do you have to draw the electric dipole? Exactly two: From left to right or from right to left.

(Don't care about the 90°-shift of the field components in the direction of the photons propagation.)
This two states we call the spin of a photon. Beside this intrinsic spin it is possible to get photons from sources that give photons a rotational moment, means the field components both together have a rotation around the axis of propagation.
The easiest way to observe the intrinsic spin is to measure a radio wave. A radio wave does contain photons of a wide range of wavelength (the source does not emit coherent light), but the photons of a radio wave are all of the same spin for every half wavelength. (This has to do with the direction of propagation of the accelerated electrons inside the antenna rod.) It has to be easy to perform an experiment to show the directions of the electric and magnetic field components of a radio wave. From the superposition of all the involved photons in the radio wave one can conclude about the nature of each photon and its spin.
BTW, Beth's experiment shows that when changing the circular polarisation of photons by quarter plates there is a repulsive force acting on the plate.


Java reconnect after network interface change

Question: I am writing a file synchronization client (in Java 1.6) that uses Sardine:
https://code.google.com/p/sardine/
When Sardine loses connection to the server (ie. network outage or change from LAN to WiFi), I am unable to reconnect until I completely stop the client and start it back up again.
I've tried the following:

spamming the connection
re-creating the Sardine object dynamically
re-packaging Sardine source code with latest Apache HTTP libs

As far as I can tell the actual networking takes place within AbstractHttpClient, but I am not sure what to try next.
Any suggestions on how I can make this thing re-connect dynamically regardless of the reason?
Answer: You need to shutdown your sardine object and create another one, example:
<code>Sardine sardine = SardineFactory.begin();

sardine.createDirectory(url);

if (sardine != null) {
    sardine.shutdown();
}

sardine = SardineFactory.begin();

// use again
</code>


Generating 3D points from Disparity

Question: Can someone point out the math involved in getting the 3d points of an image from its disparity values?I have the Image(i,j) and disparity at each of these points.What i want is the true 3D coordinate x,y,z using math equations.
Answer: Long answer - http://www.amazon.com/Multiple-View-Geometry-Computer-Vision/dp/0521540518/
Short answer.
You have the pixel scale, so for a given number of pixel disparity you can get an angle different. With the baseline between cameras and an angle you have a distance
ps. take a look at the opencv book, it has a couple of good chapters on stereo
Comment: Could you provide a more mathemetical version of this or direct me to one?
Comment: chapter12 of the opencv - you can probably preview it on google. Or the whole of the Hartley book.

Generating 3D points from Disparity


What determines the duration of larval stage?

Question: Why do insects have very long pre reproductive periods and very short reproductive periods? Is there a common characteristic that can indicate the duration of these stages or offer an explanation for the same?
Comment: I honestly find the question a bit too broad, since insects are a very diverse group that use a wide variety of substrates and environments. Is there a group of insects that you are particularly interested in? Generally, development time is often a function of food substrate quality (i.e. the food niche of the larvae) and temperature (especially for insects in a temperate environment). In the case of e.g. saproxylic (wood-living) beetles, development time is shorter for species that use the phloem of rather fresh wood and long for species that use dry core wood.
Comment: Also, in colder climates development times are longer due to shorter larval activity periods, so development times between individuals can differ e.g from 1-3 years depending on climate, location (open/sunny or closed) and substrate quality.
Answer: I actually see two different questions in your question. The first is "what determines the duration of the larval stage ?", the second is "why is this duration longer that the adult stage ?"
A) What determines the duration of developmental stages?

First, you must note that not all insects follow the same development process. Holometabolous insects (e.g. butterflies) have four life stages: egg, larva (with several instars), pupa and adult (or imago). On the other hand, hemimetabolous (e.g. bugs) only have three life stages, and some insects are ametabolous, i.e. no metamorphosis. Development time thus greatly depends on the mode of development. Of course, there can also be a huge variation within insects that have the same mode of development.
What else determines the duration of developmental stages ? (i.e. eggs/larva/pupa) A large combination of factors. Before they reach the adult stage, insects need to accumulate enough energy to undergo every developmental step and become mature. Resource quality and availability of course influence developmental "speed", but abiotic parameters such as temperature or humidity are also of prime importance. Actually, development time of many insects can be measured in degree days, which corresponds to the accumulation of temperature over time. For instance, larval-pupal development of the codling moth Cydia pomonella can go from 1 to about 6 months, according to temperature conditions.

B) Do insects have longer pre-reproductive periods that reproductive periods ?

It depends. There is a huge variation a) in the lifespan of all insect species, b) in the relative length of their developmental stages.
Some insects indeed have a very short adult life stage, relatively to their developmental stages. Mayflies are a classical example, but it's also true for many butterflies and moths of for mosquitoes, for instance.
On the other hand, it's not true for many other insects. Many Coleoptera (e.g. beetles, cockroaches) can have several-month long adult lives, sometimes way longer that their life as a larva. Bees are a more extreme example: bee queens need three weeks to become fertile, and can then reproduce during several years (same for ants).

C) Why do s̲o̲m̲e̲ insects have short reproductive periods ?

To my knowledge, the reasons are mainly ecological. Insects that have short adult lives are often fragile, flying insects that disperse a lot. They face an increased risk of predation as well as environmental fluctuations (weather, etc.) against which they are poorly protected. Besides their resources (e.g. sugar) may be scarce or poor-quality - some even do not have the ability to feed, e.g. mayflies.
What about evolutionary reasons? Developmental stages need some time because, as I said earlier, insects need to acquire a lot of energy to pass all developmental steps. I didn't even talk about metamorphosis, which is a complete cellular re-organization -that takes some time. On the other hand, adults just need to mate and/or lay all their eggs before they die. They don't need to live too long as they'll probably die soon anyway. Think about mayflies: they are less protected as free flying adults that as underwater-protected nymphae. And they'd better try to maximize egg laying in a reduced time.
Besides, note that there is a difference between potential lifespan and realized lifespan. For instance, parasitoid wasps can live up to 30 days in safe, food-abundant conditions - in the wild however, they often live just a few days.

References
https://www.terminix.com/blog/bug-facts/how-long-do-bugs-live/
Harvey, J. A., Cloutier, J., Visser, B., Ellers, J., Wäckers, F. L., & Gols, R. (2012). The effect of different dietary sugars and honey on longevity and fecundity in two hyperparasitoid wasps. Journal of insect physiology, 58(6), 816-823.
Müller, T., & Müller, C. (2015). Behavioural phenotypes over the lifetime of a holometabolous insect. Frontiers in Zoology, 12(1), S8.
Rafoss T, Saethre M-G (2003) Spatial and temporal distribution of bioclimatic potential for the codling moth and the Colorado potato beetle in Norway: model predictions versus climate and field data from the 1990s. Agric Forest Entomol 5:75–85


Kolmogorov–Smirnov statistic/distance is normally distributed?

Question: Suppose we have two populations X and Y, then compute the KS statistic/distance for samples drawn from them. Is this KS statistic/distance normally distributed? If so, how to prove it? If not, what distribution should it be? I know samples means $\bar{X}$ and $\bar{Y}$ are normally distributed according to the central limit theory.
Comment: you can't prove this because it's not true
Comment: The [Kolmogorov distribution](https://en.wikipedia.org/wiki/Kolmogorov%E2%80%93Smirnov_test#Kolmogorov_distribution) describes the relevant asymptotics when $X$ and $Y$ have identical continuous distributions.  It clearly is non-Normal.
Comment: As a fairly general principle, distributions involving *maxima* won't be normal, nor even asymptotically normal. You typically need something more-or-less "mean-like".
Answer: I'm assuming that you're talking about a case where X and Y are i.i.d. As noted, the distribution of the test statistic is not normal. Instead, it follows the Kologormov distribution. See the wikipedia entry: https://en.wikipedia.org/wiki/Kolmogorov%E2%80%93Smirnov_test#Kolmogorov_distribution
Answer: there's no such result regarding K-S statistics applied to different populations. generally, it may not even be possible to calculate K-S stat. consider $X\sim\mathcal N$ and $Y\sim\chi^2$ - these two have different domains. how do you suppose to obtain K-S stat for them?
Comment: Not sure I understand the point you are making: ys both $\chi^2$ and $\mathcal{N}$ distributions have different supports (unless you just want to think of $P(\chi^2<t) = 0$ for all $t<0$, but the K-S statistic is built around the ordering of observations in each eCDF: in such a case as you describe the K-S statistic can be calculated, and the K-S null would almost certainly be correctly rejected, yes? Or am I misunderstanding?
Comment: It's possible and even expected to compare different domains in a KS test—when comparing two samples, their domains are discrete and different; when comparing a sample and a distribution, the sample's domain is discrete and the distribution's domain is usually continuous.
Comment: @MattF. I agree, but I think you are describing the one-sample K-S test (null: the sample is drawn from the specified i.i.d. null distribution), and the OP is asking about the [two-sample K-S test](https://en.wikipedia.org/wiki/Kolmogorov%E2%80%93Smirnov_test#Two-sample_Kolmogorov%E2%80%93Smirnov_test) (null: both samples are drawn from the *same* i.i.d. distribution, whatever that distribution is.).


Initial value problem $y' = y(2-y)$

Question: I wish to solve the differential equation,
$$\frac{dy}{dx} = y(2-y)$$
with initial condition $y(0) = 1$. I'm new to differential equations, and I've never seen an equation with only one variable like this. From what I understand, it's an ordinary differential equation but I don't know what that means or what methods I should use to solve it.
Comment: Its Bernouilli's equation
Comment: Please don't change the original equation.
Answer: Hint: it is a separable DE and use
$$ \frac{1}{y(2-y)}=\frac12\left(\frac{1}{y}+\frac{1}{2-y}\right). $$

Initial value problem $y' = y(2-y)$


can we fly a rocket past the black hole in the milky way?

Question: Some information needed is facts about the black hole in a milky way.
Comment: Hello Bethany.  Please work to improve your question.  Firstly is [space.se] a better place to ask it?  If so please delete this question and ask there.  Secondly Are you asking if we have the technology now (or soon) to fly a rocket past supermassive black hole in the MilkyWay or are you asking if there is a physical law that prevents this no matter how long or what level of tech?  Do you mean the supermassive black hole or one of the many smaller black holes?  What do you mean "past"  How close do you want to be?  You must [edit] to improve your question or it will be deleted.
Comment: I'm voting to close this question because it is not about astronomy.
Comment: Hello @BethanyPalmer, *Welcome to Astronomy SE!* It's a really big deal that the Voyager 1 and 2 spacecraft have left our solar system, but it will be an unbelievably long time before they reach the distance of nearby stars, our closest neighbors. The Milky Way Galaxy is just incredibly huge, and as DavidHamment's answer points out it's measured in light years. If I google "size of the Milky Way" I get "105,700 light years"! If I google "distance to Voyager 1" I get "approximately 14.6 billion miles". However, if I google "voyager 1 distance from earth in light years" I found out that
Comment: it will take another 17,000+ years to reach just 1 light year. To learn more about the supermassive black hole at the center of our Milky Way and the stars that orbit it, we just have to keep building better and better infrared and radio telescopes. Check the question [How did they make a video of the center of the galaxy, and what is it exactly that's flashing there?](https://astronomy.stackexchange.com/q/28940/7982) for example.
Answer:
can we fly a rocket past the black hole in the milky way?

The too long, didn't read answer is "NO".

First things first, which black hole?
The central supermassive black hole is about 27000 light years away. Humanity hasn't the foggiest idea about how to realistically achieve anything close to speed of light travel. But supposing we could, the flyby is still 27000 years into the future. It will take another 27000 years for the results of the flyby to reach us. Human organizations have a hard time planning over a decade into the future. 54000 years into the future? Not a chance.
There are a good number of known stellar mass black holes that are a lot closer than 27000 light years away. The nearest confirmed stellar mass black hole is about 1600 light years away. A suspect black hole is slightly less than 1000 light years away. There might exist one that is even closer. But even if there is, we simply do not have the technology to send a vehicle to something that is 100 light years away and return a signal to us, let alone 1000 or 27000 light years away.
Comment: I am surprised that you chose to answer a question that is blatantly unclear and missing context (I was under the impression that you are generally strict with questions). Anyways, +1 nonetheless :)
Comment: @NilayGhosh Unless astronomers discover that the conjectured planet 9 exists and is a quantum black hole, the answer is an emphatic all-caps NO. I assumed the question asks about known black holes. Moreover, since the questioner wrote "the" rather than "a" black hole, the questioner most likely was asking about the supermassive at the center of the galaxy.


Distance 2 neighbors in a directed graph

Question: Consider a directed graph G in which there is exactly one edge between any two distinct vertices in G. Prove that there is a vertex in G that is in the distance-2 neighborhood of every other vertex in G. Assume that there are at least two vertices in G.
Answer: Proof by induction on $n$ the number of vertices: for $n = 2$ it is obvious. If the statement is true for $n = k$, we show it is true for $n = k+1$. In a graph with $n = k+1$ remove one of the vertices, say $v_{k+1}$, that has the maximum outdegree. Now in the remaining graph, there is a vertex $v^*$ that is in the distance-2 neighbourhood of every vertex in $\{v_1, v_2, \dots, v_k\} - \{v^*\}$. Now, again consider $v_{k+1}$, if $v_{k+1}u$ is an edge in this graph for any $u$ that has $v^*$ in distance-1 neighbourhood, then $v^*$ is in the distance-2 neighbourhood of every vertex including $v_{k+1}$. Otherwise, the outdegree of $v_{k+1}$ is smaller than $k -$ (#of vertices that have $v^*$ in distance-1 neighbourhood). Note that the outdegree of $v^*$ in this case is $k+1 -$ (#of vertices that has $v^*$ in distance-1 neighbourhood) which contradicts the fact that $v_{k+1}$ has maximum oudegree.


Show attachments on Boxed List View in SharePoint 2013

Question: I'm trying to show attachments on Boxed List View in SharePoint 2013. Hopefully this can be done with JavaScript or JQuery?
Answer: I got round this issue by using Infopath Designer to inject the filename part of the URL into a "simple line of text" field, and then a SharePoint designer workflow to build the complete URL.
The steps were as follows.
create a "single line of text" field in your list. I called mine "AttachmentURL"
Load infopath designer. and load your SharePoint list
Right click on the "single line of text" field "AttachmentURL" and select "Text box properties"

4-In the "Default Value" section next to "Value", click the "Fx" button

5-In the "Formula" dialog box, select the "Insert Field or Group" button

6-In "Advanced view", expand the "Attachments" folder, and select the ":attachmentURL" icon and click "OK" all the way back to your form

7-After making any other alterations in your form, publish the form to the SharePoint list
This gave me the attachment filename. I then used SharePoint Designer to build the rest of the URL :
Open SharePoint Designer and go to your list workflow
You will now be able to build the Attachment's URL by creating a hyperlink that follows this construction :
Comment: I guess you may have possibility using JavaScript/Jquery, but I didn't try through
Answer: You can get the list of attachments via REST calls. The boxed view doesn't usually have the ID in it unless you specifically add it.
I'd add the ID field to the box, then for each td value equal 'ID', I'd grab the id, then call the REST
/YOURSITEHERE/_api/web/lists/getbytitle('YOURLISTHERE')/items(THISIDHERE)/AttachmentFiles
Then loop through the response data.d.results, grabbing the ServerRelativeURL and the FileName, building up the links.
Then replace the row that has the ID with a row that contains the attachment links.
<code>     var queryUrl = YOURSITEURL + "/_api/web/lists/getbytitle('MYLISTTITLE')/items(" + IDYOURETRIEVED + ")/AttachmentFiles";

        $.ajax({
            url: queryUrl,
            accepts: {
                json: "application/json;odata=verbose"
            },
            method: "GET",
            success: onQuerySuccess,
            error: onQueryError
        });

    function onQuerySuccess(data) {
        if (data) {
            $.each(data.d.results, function () {
                // build up links using this.ServerRelativeUrl and this.FileName
            });
        }
        // find the row with the id and replace it with your links, or whatever you want to do
}
</code>


Does 'un-filled' form inputs slow down a website?

Question: I have a page which has a drop list inside a form. The drop list contains 'Categories' of ads.
Depending on the value chosen in the drop list, I use javascript to show/hide DIVS on the page, which all contain different form inputs for the user to fill in.
All this still inside the form!
Now, when the user has filled in all form inputs inside the 'SHOWN DIV', and clicks 'SUBMIT', the other form inputs remain 'unfilled'.
My Q is, does these 'unfilled' inputs slow down things?
Is it needed to make them (the form inputs) disabled instead of only not visible inside a hidden DIV?
BTW, the page is php based and the forms action is set to a php file.
Thanks
Answer: I guess it depends on what you mean by slow down? If you mean the processing of the form data when its posted, then no, it doesn't. If you mean the rendering of the page in the browser, than the answer is "maybe".
Inputs hidden in divs are not actually drawn on the page until your code that shows them is executed. At that point they will draw themselves, and depending on the speed of the user's system or their browser's rendering engine, it can be slow or fast.
Generally, no, you don't have to worry about performance in this regard. You can hide them in divs with no ill results.
Answer: The bandwidth required to send all of the additional form markup to the user whether or not they are visible is really the only point your application would be slowing down any. When the user submits the form only the field data for the current form is sent, so all of the other unused fields are simply disregarded.
Unless your page contains a considerable amount of extra markup to include the additional form fields, you probably need not worry about including them in the rendered HTML.
Answer: You don't need to make the other form's fields disabled, as they won't get submitted. Multiple forms don't slow things any more than other markup. Having 10 forms in a page is equally slow as similar amount of other content.
If performance is a concern to you, have you considered changing the contents of one div, instead of having one div for every option? This way you could reduce the amount of forms considerably. Not that it would matter much though – perhaps only to users on slow connections that have to download that extra content.
Answer: Firebug net panel or HttpWatch can tell you the size of the postdata sent with a request. It probably isn't a big performance hit, but comparing the size of the postdata with the hidden form fields commented out to the current size to see how many bytes are added.


0.00603581 is in my bit coin wallet how much do I own?

Question: If I have 0.00603581 in my bitcoin wallet who much do I accually own ?
Answer: You own every bit of it. Assuming you have the private key for the wallet. As far as the blockchain network is concerned, anyone with the private key is the "owner" and will transfer those funds if the correct private key is provided in the transaction request.
As long as your private key remains private and you know what it is, you own it.
Now, to send that Bitcoin somewhere else, you'll have to pay a fee. That's why miners mine the blocks. So while you (assuming above conditions are satisfied) "own" every Satoshi inside that wallet, you'll need to pay to move it somewhere else.
Note: Nuances, subjective considerations and opinions have all been crushed for the sake of brevity.
Answer: You own the same 0.00603581 BTC or 603,580 satoshis
1 BTC= 100,000,000 Satoshis


iCloud slideshow - shuffle photos

Question: I am creating a slideshow for an event that individuals are adding to a shared album on iCloud. I would like to shuffle the photos. How do I do that?
Answer: It would depend on what device you are viewing the photos.
In case of iPhone:
To view slides in random order (shuffle) turn the shuffle on.

iCloud slideshow - shuffle photos


Access the name of the gnome terminal profile from the command line

Question: Gnome Terminal allows to have different profiles. Is it possible to get the profile name under which that terminal started from the command line?
Answer: This doesn't seem to be possible, however you can find out the default terminal title, so all you need to do to distinguish between tabs or profiles is to configure different default titles.
The control sequence ESC [ 2 1 t asks the terminal to insert its title on the terminal input stream. (See Xterm control sequences for more information about escape sequences for xterm and similar programs). Specifically, the terminal (if it supports this feature; gnome-terminal does) responds with ESC ] l title ESC \.
Here's a bash function that sets the variable whose name is passed as the first argument to the xterm title, if available. It times out after one second if the terminal doesn't support the feature, and returns a non-zero error code.
read_xterm_title () {
  # Clear IFS so that read doesn't do any word splitting.
  local IFS= read_xterm_title_header=
  # $1 is expected to be a parameter name. Do a crude format check.
  if [[ $1 = '' || $1 = *[!0-9_A-Za-z]* ]]; then return 120; fi
  eval $1=
  # Expect "ESC ] l title ESC \\"
  read -p $'\e[21t' -s -t 1 -r -n 3 read_xterm_title_header &&
  [[ $read_xterm_title_header = $'\e]l' ]] &&
  read -p '' -s -t 1 -r -d $'\e' $1 &&
  read -s -t 1 -r -n 1
}
read_xterm_title title
case $title in ...

Answer: You used to be able to do this with gconftool2 and then with dconf and now you have to do with gsettings but it's a GUID, so something like this may be what you want:
gsettings get org.gnome.Terminal.ProfilesList default | tr -d \'
and in context of setting a variable:
gsettings set org.gnome.Terminal.Legacy.Profile:/org/gnome/terminal/legacy/profiles:/:$(gsettings get org.gnome.Terminal.ProfilesList default | tr -d \')/ cursor-blink-mode off

per https://wiki.archlinux.org/index.php/GNOME/Tips_and_tricks
Answer: This seems to do the trick:
gsettings get org.gnome.Terminal.Legacy.Profile:$dconfdir/":"$1/ visible-name

Stolen from here.
Comment: What does `$1` mean here?
Comment: @IgorMikushkin I can't remember and it's not immediately obvious to me, either, so apologies for the ambiguous answer!  Please let me know if you figure it out :)
 Regardless, it looks like I ultimately went the route of [this](https://superuser.com/a/1323399/114717) answer, using `gsettings get org.gnome.Terminal.ProfilesList list | tr -d "[]\',"` to get the GUID when there is exactly one profile available.
Answer: It doesn't exactly answer the question. But if you want to distinguish profiles, you may try to check a background color for example.
[[ "$(xtermcontrol --get-bg)" == "rgb:3b3b/3c3c/3e3e" ]] && echo profile-1 || echo profile-2

It returns a background color of the current profile; however, not necessarily the one that was started with, because you can change a profile on a fly.


Why did Bilbo want the ring back from Frodo?

Question: I watched Lord of the Rings,  and I saw a change in Bilbo when he had to give up the ring. He became mad and didn't want to part with it. When Bilbo was giving gifts to Frodo he gave him a shirt.  When Frodo unbuttoned his shirt the ring was there on a chain wrapped around his neck. Bilbo told Frodo he wanted to hold it again one last time, and while Frodo was rebuttoning his shirt Bilbo kind of turned into a monster and tried to get the ring back from Frodo. That part scared me, I wasn't expecting that from Bilbo. Why did he want the ring back so badly?
Comment: Ring makes ring bearer addicted. Which is explained repeatedly in movie
Answer: The ring turns its owner selfish and paranoid. It stirs up greed, petty anger, fear and other monstrous emotions. That's the corrupting power of the ring. And that's what surged up in Bilbo during that encounter.
Answer: Think of the Ring like an addiction- Frodo is just starting out with it at this point, so it hasn't affected him too much yet even though he can feel it is pretty powerful. Bilbo has had it for at least 50 years now, and he's quite, quite attached to it. It's very hard for him to give it up cold turkey, and he wants to jump back on the bandwagon. Gollum is at the point where he cannot live without it, and it drives everything he does and tries to get at.
Answer: As I understood that scene was meant to emphasize the power that the ring could wield over the holder even after just a few years of Bilbo having it in his ownership. The stark contrast showed the audience that Bilbo's' personality itself had not changed THAT much but in matters concerning the ring any former holder would become very overprotective and greedy basically the same personality traits that multiplied a hundredfold lead a person to become Gollum-like(yes I am going to invent that word)
Answer: This was not first time that Bilbo has tried to keep Ring with himself. Initially, also Gandalf needed to force him to give Ring. This is effect of ring on peoples that they become attached or attracted towards the Ring.
We saw this effect in movie multiple times over different persons like Isildur, Boromir. Even Gandalf was not ready to carry it to Mount Doom as it will corrupt his mind.
Frodo also hesitated in the end while reached to Mount Doom due to same effect. Even when he went through to destroy it and knew that it is evil.
This effect is more on Ring Bearer or person who keeps the ring with himself. You can see Gollum has dedicated his life for his percious "Ring" and even in end , while dying in Doom he kept his hand up trying to save.
Wikia also confirms these effects :-

For mortals, the ring had several side effects, most of them negative. Perhaps the first was that the bearer of the Ring almost immediately began to develop an unusually strong attachment to it, and would be unwilling to give it up or abandon it.
Answer: Firstly you have to examine what the ring is. It is an extension of Sauron's will, a physical item that Sauron imbues with his own spirit through magical means in an effort to not only make him stronger but to extend his dominance over other magical rings that are owned by the leaders of the different races of Middle Earth. The creation of the ring follows a period of time in which Sauron along with the Elven smiths of Eregion, most notably Celebrimbor crafted 19 rings of power for the chief Lords of the children of Iluvatar. Three were given to the Elven Kings. One ring to Gil Galad High King of the Noldor and the ally of Elendil High King of Gondor and Arnor joining forces with the Numenorean during the War of the Last Alliance. After Gil Galad was slain by Sauron in that war the ring was kept by Elrond. Another ring was given to Cirdan the shipwright, the oldest living elf in Middle Earth during the second age and Lord of the Grey Havens. Cirdan was gifted with foresight and willingly gifted his ring into the protection of Gandalf when the Istari arrived in Middle Earth much to the chagrin of Saruman, their leader. The third ring was gifted to Galadriel, the lady of Lorien who continued to hold onto her ring throughout the Third Age.
Sauron also gave seven of these rings to the Dwarf Lords and Nine rings to great Kings of Men. The targets of Sauron's rings all held some degree of influence over the different free peoples and if Sauron could dominate them then he would control all life on Middle Earth. I've highlighted the Elven rings specifically because out of the 19 rings (excluding the numerous practise attempts) that were crafted by the Elven smiths of Eregion, those three were crafted by Celebrimbor alone and were notably free of the influence of Sauron. Celebrimbor was himself a descendant of Feanor, who had crafted the three Silmarils from the light of the two trees before the First Age of Middle Earth, and was considered to be the greatest smith in Middle Earth at the time. Celebrimbor was also, along with Narvi the Dwarf, the creator of the Doors of Durin that sealed the Western Gate of Moria.
At the time these rings were constructed Sauron was still able to take a fair form, the form of Annatar, which he used to deceive the Noldor and was therefore able to use the Eregion smiths, called the Gwaith-I-Mirdain to forge his rings. Celebrimbor however distrusted Sauron which is why he chose to make the Elven rings alone and after their construction, hid them from Sauron. After the 19 rings had been made Sauron had in secret been creating the One Ring with the sole intent of binding the others to him and thus the wearers of these rings would be under his sway and by extension he could dominate the population of Middle Earth.
Because Celebrimbor had secretly crafted the Elven rings alone, when Sauron came to place the One Ring on his finger, the Elves became immediately aware of his presence and removed their rings. This infuriated Sauron who declared open war on the Elves demanding the rings be handed over to him. The elves however hid their three (the greatest of the rings of power) as well as passing one of the rings onto the Dwarves of Khazad Dum who had good relations with the Gwaith-I-Mirdain. Sauron however was able to reclaim the other 15. Of those 15 he gifted 6 to the Dwarves whilst nine he gave to Men knowing they would bend more easily to his will. Of the recipients of the rings the nine Men would eventually be dominated completely by the will of Sauron and became the Nazgul, his chief lieutenants. The seven Dwarf Lords would initially only see great increases in their wealth which over time instilled in them an overwhelming greed for treasure that would in turn lead to their ruin.
As for the three Elven rings, they were not created with the intent of war or dominance but in preservation of the Elven domains and healing and so they enabled their users to protect the Elven kingdoms that remained in Middle Earth. All the rings however were bound to the One Ring and whoever wore the One Ring could see the thoughts of those wearing the three elven rings despite Sauron's influence not being involved in their construction. All of these rings however had their power tied to the One Ring so when the One Ring was destroyed in Mount Doom, the other rings lost their power.
This is important to know in relation to the One Ring because it demonstrates its purpose. It is an object created solely with the intent of dominating all life in Middle Earth. Not only that but it was created by a being that used deceit and manipulation to achieve many goals. To look at the Fall of Numenor for a moment. At the time of its fall, Numenor was ruled by a King known as Ar-Pharazon who was an extremely capable martial leader. Ar-Pharazon was incredibly prideful and when it came to his attention that Sauron, who was dwelling in Mordor at the time, was calling himself the Lord of Men Ar-Pharazon decided to challenge Sauron's power directly. He marched on Mordor with an army so powerful it caused Sauron's forces to desert him and Ar-Pharazon would take Sauron back to Numenor in chains.
Sauron however feigned awe at Ar-Pharazon's might and upon landing in Numenor, worked to gain the King's trust which he accomplished through flattery, lies and half truths. Eventually Ar-Pharazon made Sauron his chief advisor who managed to corrupt the King and turn him to the worship of Morgoth claiming Morgoth could help the King cheat his own mortality. Sauron was able to erect a great temple to Morgoth on the island, persecute the faithful and chop down the white tree of Numenor. As the King grew old Sauron convinced Ar-Pharazon to take immortality by force and convinced him to assault the Undying Lands. The King reached the shores of Valinor with a great fleet and the Valar laid down their guardianship of the world calling upon Iluvatar to intervene. Eru Iluvatar sank Ar-Pharazon's fleet along with the island of Numenor allowing only the faithful Numenorean's under the leadership of Elendil and his sons Isildur and Anarion who sailed to Middle Earth where they founded the kingdoms of Gondor in the south and Arnor in the north.
With Eru's sinking of Numenor and reshaping of the world to separate the Undying Lands from the world (stopping mortals from travelling there), Sauron himself suffered his first "death" as his physical body was destroyed, though his spirit was not diminished and he escaped with the ring back to Mordor where he rebuilt a new body, though he could no longer take the fair form of Annatar. From this you can see how skilful Sauron was with words alone. He was able to manipulate a King that had conquered him and taken him prisoner into trusting him completely to the point that he even assaulted the Valar on Sauron's instruction.
Within "The Lord of the Rings" we know that Sauron poured an extension of his spirit into the One Ring when he crafted it, linking it to him and allowing him to dominate the other rings. The One Ring itself is often described as if it is alive, with a will of its own, desperately seeking to return to its master Sauron. This is a fact that Gandalf informs Frodo of. Aragorn also tells Frodo that the Nazgul will always be drawn to the One Ring because of its connection to them and Sauron. The Ring even manipulates Gollum into at first stealing the Ring from Frodo and then later into taking them to Shelob where the Hobbits will likely die and Gollum will claim the Ring once again. If Gollum is successful he will likely use the Ring again to seek out food as he does in "The Hobbit." As soon as he wears it, the Nazgul will come for him.
Gollum is a being that has been in possession of the Ring for a considerable amount of time prior to the events of "The Hobbit." We see how deeply the Ring has affected him to the point where Gollum has developed an entirely new personality, that of the Ring. In fact this personality had become so dominant that Gollum had completely forgotten his own identity as Smeagol which he only begins to remember again after Frodo brings it up. Bilbo by the time of "The Lord of the Rings" has already had the Ring in his possession for 60 years. His 111th birthday is even explained as being an unusual age for a Hobbit to reach. When Gandalf meets with his old friend again he is surprised to see that Bilbo despite his advanced age still appears quite youthful.
This is the Ring affecting Bilbo physically. Because of the events of Bilbo's birthday, Gandalf begins to suspect that the magic ring is something more than it seems which sees him go on his quest to gather information which leads him to the conclusion that Bilbo's ring is indeed the One Ring. When Frodo meets Bilbo in Rivendell and Bilbo momentarily tries to attack Frodo, this is merely an extension of the impact the ring has had on Bilbo. The Ring after all seeks to dominate all life in the name of its master, when someone other than Sauron uses the Ring, its sole intent is to corrupt that individual into submitting to Sauron as a means of returning to Sauron. The easiest way to corrupt an individual is to appease their desire. For someone like Boromir for example, the Ring preys on Boromir's desire to protect the people of Gondor by influencing his thoughts and making him despair in the belief of what may happen if he doesn't use the Ring to save Gondor. This is why Gandalf refuses to take the Ring and even go as far as to tell Frodo that even if he took the Ring with a desire to do good, through him the Ring would wield a power too terrible and evil to imagine.
In essence the Ring is simply a manifestation of the old adage, "The road to Hell is paved with good intentions." It makes its user desire the power it promises by preying on desire. Therefore Bilbo in his 60 years of possessing the Ring, though perhaps slower than most beings given Hobbits seemingly natural resilience to the Ring, is also corrupted by it. We are informed directly of the odd physical appearance of Bilbo despite his age which is a clear indicator of one of the Rings many abilities, sustaining the bearer granting them an unnatural lifespan. If Tolkien has indeed examined the importance of this detail then it goes without saying that the Ring has also had a mental impact on Bilbo. After all Gollum's mental state is about as twisted as his physical appearance.
Bilbo wanted the Ring back because its corrupting nature had left him desiring it, just as Gollum desired the Ring and Isildur before him. Both for different reasons. Gollum prized it as a beautiful treasure, similarly to Bilbo who also saw it as a useful object. Isildur prized it as a trophy and symbol of his might, having vanquished Sauron in battle. Boromir desired it to help his people, as did Galadriel though she was able to resist in a fashion similar to Gandalf. Saruman desired it as a means of domination himself. Frodo himself succumbs to the Ring's corrupting influence. Other than Tom Bombadil who's nature is a mystery, only Faramir seems to be able to resist the corrupting influence of the Ring which is interesting as the Ring's effect on Men was greater than what it held over other races largely because of the Ring's ability to sustain life unnaturally allowing the Ring to deceive Men into believing they could cheat their mortality.  In resisting however Faramir states:

"But fear no more! I would not take this thing, if it lay by the highway. Not were Minas Tirith falling in ruin and I alone could save her, so, using the weapon of the Dark Lord for her good and my glory. No, I do not wish for such triumphs, Frodo son of Drogo."

He is a man of honour and vows to hold true to his word. That's not to say the Ring doesn't try and tempt him in some way but Faramir who sticks to his word refuses to even consider using the weapon of such an enemy for his own devices even when not entirely certain what it is the Hobbits carry. When he does discover that Frodo and Sam are carrying the Ring, he also learns from Sam how the Ring had corrupted his brother and realises the peril of such a thing which allows him to completely resist it. Basically none of the characters in Middle Earth save Sauron and Tom Bombadil could remain completely unaffected by the Ring's power and those that had been around it for longer and benefitted from it in some way, desired it far more greatly than others.
Answer: In short: The ring's influence on him (similar to how Gollum wants the Ring back as well). In the hands of Bilbo, the ring is far easier to be reclaimed by Sauron, as such it tries to manipulate him once again.
Comment: I don't think Gollum was evading Sauron so much as Sauron wasn't ready to do anything yet. When he was ready to put things in motion, Gollum lost the ring and Bilbo found it. It was at that point, Sauron needed the ring to come into the light.
Comment: Mmm...not sure about that. If Sauron was able to manipulate it that much, how did Gollum evade Sauron for a few hundred years? What's not to say that the ring wouldn't have hidden with Bilbo the same way?
Comment: "In the hands of Bilbo, the ring is far easier to be reclaimed by Sauron" - There is no evidence of this. How did you come to this conclusion?
Comment: @Mario Your conclusion is non canon. There is nothing in the book to support this. Thats the reason i asked.
Comment: @BobbyAlexander First of all, Bilbo is older than Frodo, even with his life being prolonged by the ring. Also he used the ring "just for fun", whereas Frodo always tried to avoid using it. And last but not least, Bilbo had the ring for a much longer time, as such I'd assume the influence over him would be a lot bigger.
Comment: @BobbyAlexander Which part? Can't say for sure for the first two points, but I'd say the last one is for sure.
Comment: I meant this: In the hands of Bilbo, the ring is far easier to be reclaimed by Sauron. How did you arrive at this?
Comment: Bilbo travelled alone now, which makes him a far easier target (there's more than one occassion where Frodo alone would have been screwed). Also the bigger influence made it easier for the ring to be used (so the black riders would find him faster). Not to forget Bilbo aged without the ring (I assume this isn't movie-only?), and I don't think the ring would make him younger again.


Should I prefer PhD programs with "higher quality" students?

Question: In choosing between PhD programs A and B (for pure math in the US), some professors have remarked to me that A is favorable because it is more selective and consequently has stronger students than B. Is this a factor I should consider? Both institutions have several of the top researchers in my subfield so quality of advisors is not an issue.
Comment: Stronger grad students or stronger undergrads? The former is significantly more important for you as a grad student. That said, all else being equal, either is an advantage.
Comment: "Advisor" may be the most important thing. Still, I think it's not so much the "strength" of the grad students, but the _atmosphere_. E.g., a sluggish, dreary, provincial atmosphere will drag you down, and tend to color your judgement... possibly leading to your doing less than you could. On the other hand, high-energy situations can sometimes be pointlessly nasty. So it depends on the atmosphere (not just the intensity), and on your preferences.
Comment: Will you feel motivated? The most important thing is the supervisor and the topic. The rest will find itself.
Comment: @darijgrinberg I did mean grads.
Comment: Sometimes a visit helps narrow things down.
Comment: If the level of the typical graduate student is far above your level, you probably won't do well.
Answer: It's worth considering in your case because your graduate experience will in part be shaped by your peers. Your peer group in graduate school will help (or hurt) your research and teaching experiences --- at some schools your peers will help lift you up and inspire you, at others they will underwhelm you.
Your peers will also help with networking. The people who are finishing when you arrive in grad school will be useful people to get advice from when you go on the job market, as they will have recently been through it themselves.
I'm in the finishing stages of a PhD right now and I've benefited a lot from knowing the top-notch students who had come before me. I learnt from them, they have given me lots of feedback over the years, they've helped me with networking, etc.
Answer: Most people would say that a degree from a more selective university is more valuable.
Most people would say that high-quality peers is a great thing to have.
Neither of these things is more important than your degree of fit with prospective advisers. Neither of these things is more important than your personal motivation and happiness.
Find a grad school that makes you feel really good about your studies rather than maximizing the future value of your degree.


Solve this system equation $\lfloor xy\rfloor=12,\lfloor x^2\rfloor+\lfloor y^2\rfloor=25$

Question: Let $x,y\in R$.solve this system equation
$$\begin{cases}
\lfloor xy\rfloor=12\\
\lfloor x^2\rfloor+\lfloor y^2\rfloor=25
\end{cases}$$
I have found  integer solution $(x,y)=(3,4)$ How to Find the other
Comment: $3<x<4, 3<y<4 , 12<xy<13$ $\sqrt{9+k}\leq x< \sqrt{10+k}$ $\sqrt{16-k}<y<\sqrt{17-k}$ there exist a solution about each integer k.
Answer: There is a non-countable solution set $S$ and we expose here a subset $T$ of $S$.
We have
$$\begin{cases}x=\lfloor x\rfloor+\{x\}\\y=\lfloor y\rfloor+\{y\}\end{cases}\Rightarrow\begin{cases} xy=\lfloor x\rfloor\lfloor y\rfloor+\lfloor x\rfloor\{y\}+\lfloor y\rfloor\{x\}+\{x\}\{y\}\\x^2=\lfloor x\rfloor^2+2\lfloor x\rfloor\{x\}+\{x\}^2\\y^2=\lfloor y\rfloor^2+2\lfloor y\rfloor\{y\}+\{y\}^2\end{cases}$$
A clear solution is the Pythagorean $(x,y)=(3,4)$. Taking $x=3+\{x\}$ and $y=4+\{y\}$ one has
$$\begin{cases}xy=12+3\{y\}+4\{x\}+\{x\}\{y\}\\x^2=9+6\{x\}+\{x\}^2\\y^2=16+8\{y\}+\{y\}^2\end{cases}$$ We still have the two given equations when $\{x\}$ and $\{y\}$ satisfy the system
$$\begin{cases}0\lt3\{y\}+4\{x\}+\{x\}\{y\}\lt 1\\0\lt6\{x\}+\{x\}^2+ 8\{y\}+\{y\}^2\lt 1\end{cases}$$ In particular it is satisfied making $\{x\}=\{y\}$ which gives
$7\{x\}+\{x\}^2\lt1$ and $14\{x\}+2\{x\}^2\lt1$ which reduces to $7\{x\}+\{x\}^2\lt \frac 12$ so we can choose  $\{x\}\le0.07$. Hence our subset $T$ is formed by all the positive
ordered pair $$(x,y)=(3+\{x\},4+\{y\})\text { with }   \{x\},  \{y\}\le 0.07$$
Example.- $x=3.07$ and $y=4.07$ hence $7(0.07)+(0.07)^2=0.4949\lt \frac 12$
consequently  we can choose arbitrarily $ \{x\},  \{y\}\le 0.07$.
Note.- There are other subsets without the integer part $3$ and $4$.
Answer: For all $(x,y)$ in  the solution set  $S$ one has $xy\geq12$, $(-x,-y)\in S$, and $(y,x)\in S$. It is therefore sufficient to determine the set $S':=S\cap\bigl\{(x,y)\>\bigm|\>0\leq x\leq y\bigr\}$.
When $(x,y)\in S'$ then $$0\leq k:=\lfloor x^2\rfloor\leq\lfloor y^2\rfloor=25-k\ ,$$
hence $0\leq k\leq 12$. It follows that $S'$ is contained in the union $U:=\bigcup_{0\leq k\leq 12} R_k$ of the rectangles
$$R_k:=\bigl\{(x,y)\>\bigm|\>\sqrt{k}\leq x<\sqrt{k+1}, \quad \sqrt{25-k}\leq y<\sqrt{26-k}\bigr\}\qquad(0\leq k\leq 12)\ .$$
Now $S'$ is the intersection of $U$ with the "hyperbolical band"
$$B:=\bigl\{(x,y)\>\bigm|\>x>0, \ y>0, \quad 12\leq xy<13\bigr\}\ .$$
For all $(x,y)\in R_k$ one has $x^2y^2<(k+1)(26-k)=26+25k-k^2$. Here the right hand side is maximal when $k=12.5$, and for $k=6$ one obtains $x^2y^2<140$. It follows that $R_k\cap B=\emptyset$ when $0\leq k\leq 6$. On the other hand the point $\bigl(\sqrt{8}-\epsilon, \sqrt{19}-\epsilon\bigr)$ lies in $R_7\cap B$, and the point $\bigl(\sqrt{12},\sqrt{13}\bigr)$ lies in $R_{12}\cap B$.
Summing it up, we can say that
$$S'=\bigcup_{k=7}^{12} \bigl(R_k\cap B\bigr)\ .$$
Answer: Form the first equation,
$$12\le xy<13$$ which is the area between to hyperbolas.
From the second equation,
$$\begin{cases}m\le x^2<m+1\\n\le y^2<n+1\end{cases},$$ with $m+n=25$. These are rectangular tiles that approximately fill a circle of radius $5$.
Looking at the solutions with a grapher, there are actually few tiles that intersect with the two hyperbolic stripes. They are such that
$$mn<13^2\land12^2<(m+1)(n+1).$$
There are $12$ solutions in the positives, from $m=7,n=18$ to $m=18,n=7$.
A tile is fully filled when
$$12^2\le mn\land(m+1)(n+1)<13^2$$ and this does not occur.
Hence the solutions are a few dented tiles.


How do I collect loot stored in my town hall?

Question: How do I collect loot stored in my town hall and how does it get there?
Comment: It *is* a storage. From the TH, you can spend it directly on stuff.
Answer: Your town hall simply acts more1 like a storage as of the TH11 update. It contains up to a certain amount of loot (see here for a chart on how much) in it that will be obtained if and only if the town hall is destroyed. There is no way to prevent it from being stored in there, nor to remove loot from it.
See here for more information on loot distribution.
1: It used to only hold 1k gold and elixir.
Answer: You cannot collect the loot from your Th. It is already included in your available amount. Now the CC loot is now in the treasury. Click on the CC to find the treasury icon. Your daily Star bonus willaccumulate there as well. As always, when your CC is full, you lose the overflow.
Answer: If you remember when you were a TH 1 (I know, you were so cute), your only storage was your TH. You didn't have any storage nor buildings at all, only your TH as your entire village. How could you have bought those first gold and elixir storage if you didn't have a way to store those resources already? It functions as both a storage and a building. Just like how you can't control specifically how much gold and elixir is in a storage, you can't "drain" your TH resources into your other storages.


why does the number of transactions per block reduces with increase in transaction fees?

Question: While looking in mempool i saw with increase in sat/vbyte the number of transactions decrease.
are they somehow related?
Comment: Hi sat crazy, could you clarify what data you are looking at for your observation? The title makes me think that you are looking at past blocks and see that higher feerates correlate with fewer transactions, but the body of your post makes me think that you are looking at a mempool visualizer.
Answer: The way I interpret your question, you were looking at a mempool visualizer like the following:
And you are asking why there are strictly fewer transactions for every fee rate band with higher feerates.
Most of these mempool visualizations don't give the count of transactions in each band, but the count of all transactions in the feerate band and above. If you carefully inspect the legend, you see that e.g. the highlighted row says "8+: 6,811 tx" and not "8-10: 6,811 tx". The row's number includes all transactions that pay at least 8 sat/vB.
Answer: The number of transactions in a (full) block depends on the average transaction size, which in turn depends on the number of inputs and outputs of a transaction (and also on the specific output types used). There are several main types of large transactions:

Batched payment – one transaction paying multiple participants at once. Used extensively by exchanges to save on fees. (example)
Consolidation – a user consolidating their many unspent outputs into one to save on future fees. (example)
CoinJoin – many users mixing coins within a transaction in a way that breaks chain analysis heurestics. (example)

I don't think any of these occur more frequently during times of higher fees, and it's reasonable to assume consolidations will be happening when fees are low. So if there is any relationship between fee rate and number of transactions in a block, my guess is that it's actually the opposite of what you've observed.
Comment: @satcrazy I've never seen a block with unused space when there were enough transactions in the mempool to fill it (excluding empty blocks which is a different matter entirely).
Comment: why is it then that some blocks get filled with less number of transactions (i mean <1MB)  even when there are many transactions in the mempool.
Answer:
why does the number of transactions per block reduces with increase in transaction fees?
While looking in mempool i saw with increase in sat/vbyte the number of transactions decrease. are they somehow related?

I am assuming you are trying to compare fee rate and transactions per block. I have shared the charts comparing both since 2016.
There are only 3 major spikes in fee rate chart and I don't see transactions per block reducing in that period when fee rates increased. There could be some correlation with BTCUSD price or other things but its unrelated to question.

First chart: BTC/MB
Second Chart: Tx/Block

Date
Tx/Block Range
BTC/MB Range

Dec 2017
2100 - 2400 (10% segwit)
4 - 10

May 2019
~2400 (30% segwit)
0.9 - 1.7

Apr 2021
~2000 (50% segwit)
0.7 - 2.5

29 November 2021:

Tx/Block
BTC/MB

2345 (80% segwit)
0.05


How do I get cx_Oracle to work on 64-bit Itanium Windows?

Question: I'm running Windows Server 2003 on a 64-bit Itanium server which is also running 64-bit Oracle 10.2, and I'd like to install cx_Oracle for Python 2.5.  I've used cx_Oracle before many times on both Windows and Linux, and I've also compiled it before on 32 bit versions of those platforms, but I've never tried an IA64 compile.
None of the binary builds of cx_Oracle at http://cx-oracle.sourceforge.net/ are 64 bit, and I get an error after installing any of them when trying to run import cx_Oracle so I figure the thing to do is to compile it from source.
When running python setup.py build then I get the error that Python was built with Visual Studio 2003 and that I need something which can produce compatible binaries.  I have Visual Studio 2005, which apparently doesn't fit the bill due to linking against a different version of the C standard library, and probably for other reasons as well.  Unfortunately, Visual Studio 2003 is no longer available for download, and I'm not sure where to get it.
So I download MinGW from http://sourceforge.net/projects/mingw/files/ but this is also only available in 32 bit form.  I go ahead and give it a try anyway, but it gives me an error during compilation about one of the Oracle DLLs I'm linking against having an invalid file format.
At this point I've got a lot of options, and I'm not sure where to place my efforts:

I could download the 64 bit MinGW from http://sourceforge.net/projects/mingw-w64/ and try using that, except that it only seems to be available as source, so I'd have to compile the compiler, probably using Visual Studio 2005.
I could try using an x86 32 bit build of Python and then download the Oracle Instant Client SDK from http://www.oracle.com/technology/software/tech/oci/instantclient/htdocs/winsoft.html and then use that to build cx_Oracle.  I'd probably have to set my ORACLE_HOME to the client so that it didn't try linking against the 64 bit server DLLs, but this seems like it might work.
I could try compiling Python itself from source, using Visual Studio 2005, so that I could then use Visual Studio 2005 to build cx_Oracle and not worry about binary compatibility issues.  I've compiled Python from source many times on Linux and never had any problems, so I'd like to believe that it's just as simple on Windows.
I could try to figure out how to make Visual Studio 2005 link against the right DLLs and thus produce compatible binaries in that manner without needing Visual Studio 2003.  Intuitively it seems like Visual Studio should be able to produce compatible binaries with older versions of itself, but almost all of my compiler experience is with gcc so I don't really know.

I'm just really not sure where to direct my efforts.  Does anyone have any suggestions about where to go next?  I can copy/paste some of the specific error messages I've gotten if that would be helpful.
I'd especially love to hear from anyone who's ever gotten cx_Oracle to work on a 64 bit Itanium version of Windows - I can't be the first to try this.
Comment: Since the mingw-w64 project on sourceforge.net is moving to mingw-w64.org i suggest to use [mingw-w64.org](http://mingw-w64.org)
Answer: I ended up going with Option #2: I downloaded the 32-bit Oracle Instant Client, then compiled cx_Oracle for 32-bit Python with the instant client.  So everything involved is 32-bit, and I'm just not using any IA64-bit executables, and this works just fine.
If I had an IA64 compiler, I'd try Option #3, but it turns out that Visual Studio Pro doesn't support the IA64 platform, and we'd need to spend a lot of money to upgrade to whatever's higher than Pro.
Answer: I read this yesterday and am not suprised to see that nobody has answered. It is a very specific and complex question.  While I do not have direct experience with many of the tools you are dealing with I have delt with the issues surrounding incompatabilities with different compilers and binaries.  For what its worth 3. sounds like your best bet.