how to compounding more that one matrixs into other matrix?
How do you concatenate matrices? And how do you make block matrices?
Integrating MySQL with Python in Windows Say I have a cologne bottle of 100 ml that I want to carry in my hand luggage on a plane trip.  100 ml is the limit so it should be fine for the transport regulations (if not, please let me know!).  The problem I always encounter is regarding the storage of the bottle: how to prevent it from leaking?  What I normally do is to put it in a plastic bag, so that the possible loss remains there. It is fine, only that the bottle ends up quite wet.  What would be a better approach? My Minecraft app now only has the option of "play" and there is no "play on realms" to be found!  I downloaded - and paid for - the multiplayer app, but there doesn't seem to be a way to get to any realms on that app either. How to show $\lim_{n \to \infty} \sqrt[n]{a^n+b^n}=\max \{a,b\}$? Why use the 'ref' keyword when passing an object? If I am passing an object to a method, why should I use the ref keyword? Isn't this the default behaviour anyway?  For example:  class Program {     static void Main(string[] args)     {         TestRef t = new TestRef();         t.Something = "Foo";          DoSomething(t);         Console.WriteLine(t.Something);     }      static public void DoSomething(TestRef t)     {         t.Something = "Bar";     } }   public class TestRef {     public string Something { get; set; } }   The output is "Bar" which means that the object was passed as a reference. Storing datetime values in Shapefiles using QGIS? I have a shapefile with date in a string field. I create a new field with date type and use the calculator to make the conversion. But the result only provide the date part, the time part is removed. Even when the preview show the correct conversion.  Here you can see the original string field time and the result date time2. And the use of the conversion function to_datetime() and the preview result at the end    If you go to the layer properties you can change the edit mode to date/time. Then if go to the data and try to edit time2 you get the current date/time. So is possible save date and time in the same field. But the update tool still doesn't work as expected      As J.R said. Even when you can change QGIS edit to allow Date/Time the save to shapefile will discard the time. Currently, if you access a deleted question you will get a short message informing you that the question has been deleted. However, if you click on a direct link to a deleted answer or comment (which you can get via notifications), nothing is displayed.  This is naturally quite confusing as you will get the message about a new answer or comment via notifications, click on the link and simply see nothing.  Therefore, I propose to display some sort of message to the user, informing her/him that the answer or question has been deleted. Note that this is different from always showing a deleted answer/comment, as I specifically request it in case you access the specific URL.  One example for a comment would be:   One example for a deleted answer is:   This question is related to ,  but requests a feature to circumvent the problem altogether. Clearly if $\lambda$ is an eigenvalue of $A$ then $p(\lambda)$ is an eigenvalue of $p(A)$ where $p$ is a polynomial. And there are cases where $A$ may have eigenvalues other than these.   Is there a general rule for finding all eigenvalues of $p(A)$? Does it depend on the field from which the elements of $A$ are taken? Are their any partial solutions to this problem? How Do You Use An Image As The World Background? I have been developing a few python addins and I'm just wondering what is the best way to re-compile the addin anytime I edit the script.  Currently, if I make an edit to the script, it seems like I have to   Close ArcMap Go to My addin folder and double click the 'makeaddin' python file Double click the 'Python Addin File Restart ArcMap for the changes to come into effect   If I don't do these steps, then the edits aren't recognized. This gets pretty annoying and time consuming when I want to place maybe a simple print line somewhere or I do a small edit just to test a result.  Is there a better way of doing this? Is there a free site to play Yu-Gi-Oh? In how many ways can $500$ indistinguishable students select books from $10$ titles if no more than $20$ copies of one particular text are selected? Assume that there are an arbitrarily large number of copies of ten diﬀerent discrete math books (which we will call titles) for cmsc250. Each student must choose one title as the course text book. Assume that the ﬁve hundred students taking the course are indistiguishable.  How many diﬀerent ways can the students choose titles, if Epp must be chosen by at most twenty students?   I understand that this is a stars and bars problem where the formula would be ${n+r-1}\choose{r-1}$, but whats throwing me off is the "at most" parameter of the problem. My answer is ${480+9-1}\choose{9-1}$ My reasoning was that we now have one less "bar", and that should be shown by lowering $r$ by 1  Am I approaching this the right way? Sorting an Array of Objects in PHP In a Specific Order I have two arrays in PHP. The first array ($author_array) is comprised of user_ids in a particular order, like so: (8, 1, 6)  The second array ($user_results) is comprised of an array of objects like so:  Array (     [0] =&gt; stdClass Object         (             [ID] =&gt; 1             [user_login] =&gt; user1         )     [1] =&gt; stdClass Object         (             [ID] =&gt; 6             [user_login] =&gt; user6         )     [2] =&gt; stdClass Object         (             [ID] =&gt; 8             [user_login] =&gt; user8         ) )   I'd like to "sort" the second array so it's in this order, which matches the order of the values in the first array of (8, 1, 6). So it'd look like this:  Array (     [0] =&gt; stdClass Object         (             [ID] =&gt; 8             [user_login] =&gt; user8         )     [1] =&gt; stdClass Object         (             [ID] =&gt; 1             [user_login] =&gt; user1         )     [2] =&gt; stdClass Object         (             [ID] =&gt; 6             [user_login] =&gt; user6         ) )   I'm weak on data structures. How could I do this? :-)  Thanks in advance for your help!  -Bob Connecting to Oracle database with ArcGIS for Desktop? Pointer Arithmetic Does anyone have any good articles or explanations (blogs, examples) for pointer arithmetic?  Figure the audience is a bunch of Java programmers learning C and C++. Is it possible now to use microtype with opentype fonts? bases and binary I can not figure this out.   I started off by making a table and putting the base(2) on one side, the number in the middle and the remainder in the third row and for 2010 I got 11111011010 but I cant find the next two numbers please help and please explain in detail.  Thank you =)   to express 2010 in base 2, we use exactly 8 ones and 3 zeros. find the next two integers in base 2 that use the same number of ones and zeros For those who duplicated my previous question - ; am NOT asking how to install Skype for God's sake!!   The question was rather - I already have Skype installed, the thing is there is no possible option for me to do group video call or group screen share. The interface itself resembles the times when Skype was newly born. While on Windows, Skype's latest version is around 6.(something), here it's only 4.3. In Windows group video call is now free on Skype, here I can't even do video call! I think this is a major drawback for an otherwise so good OS! Is there anything that can be done about it?  Thanks for any help!  For those who don't have an answer for me, I still thank you for at least understanding my question!!  Have a good day! What happens when you plug two sides of a cable to a single networking device? What is likely to happen when you plug two ends of a network cable to a single switch/router? Will this create problems on the network, or just be ignored? motion tracking : how to extract 3d position from selected 2d tracker I already solve my camera and created 3d scene successfully. Now i want to do 2d track the original clip and by using solving data, i want to extract that specific point into 3d coordinate (as empty object or plain axes). How can i do this ?  Thanks