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Both Mathematica and Maple have no procedure for stopping an out-of-control, non-terminating computation, except for pulling the plug on the comptuer. Whenever I give Maple a computation which is too big for it to handle, it not only does not return an answer, but it crashes my entire computer. It makes dragging up any other windows nearly impossible. There is no "stop" or "escape" key. And, even after I successfully terminate the program by right-clicking and closing the file, I hear my computer still grinding away as if it is still computing for Maple, and my computer is still (practically) frozen. The only way to fix this is to reboot my computer - and then, only if the computer will respond to my mouse to allow it to get over to the shut down button. Often, it will not, and the only way I can reboot is by physically pulling the plug and replugging. Even the physical reboot button will not work under these conditions.

I think it would be a good idea for Maple to have some way in the software of shutting down a computation before it gets out of hand, rather than me physically pulling the plug and replugging.

Also, none of the suggestions about creating matrices using the sidebar dropdown list helped. I see that that sidebar dropdown matrix command created some kind of a matrix, but not one I could do anything with (determinants, inverses, etc.)

There certainly is a Stop button, but it does not always work: see recent discussions PUBrown Blowfish Metallic Slay Black Bell Madera Deluxe Micro Leopard Autumn 4X4q7 and here.  It does sometimes happen that a Maple kernel is still running even though the Maple window has closed.  If you're in Windows XP, Ctrl-Alt-Del should bring up a Task Manager, where you can end the mserver.exe process.

As for Matrix in the sidebar, here's a step-by-step example.

1) Place the cursor in a 2D input region.

2) In the Matrix sidebar, set Rows to 3 and Columns to 3, click Insert Matrix.  A 3 x 3 Matrix appears in the input region, with magenta-coloured entries m[1,1] etc., and the top left entry highlighted.

3) Type the top left entry, followed by the Tab key to move to the next entry, and so on until you have all the entries.  Then press Enter.  The Matrix appears as output.

4) If you want to work with this the traditional way, assign it to a variable and use the usual LinearAlgebra functions.  Or if you prefer point-and-click, right-click and choose Standard Operations and then Determinant or Inverse.

 

 

 

The described behaviour sounds like what happens when the machine runs out of physical, hard memory and then starts to use virtual memory. Virtual memory as RAM imitated by a hard-disk is much, much slower than usual RAM. The shifting of memory in and out of such virtual space (swapping) is so slow that the machine can appear to be frozen (even if it's only temporary, but for a long time).

If the machine is greatly "swapped out", then the OS itself may be very slow. And hence it may appear that the Maple red "stop-sign" button is not functioning.

Computer algebra systems, which do exact symbolic computations, are well-known to consume vast amounts of memory. It's often intrinsic to exact symbolic computation, some might say.

I would suggest that you find out how to use the Maple start-up options which control the amount of memory that can be allocated. On Unix/Linux/OSX this can be done by launching the program with the -T switch. I am not sure how it is done using graphical launcher buttons on MS-Windows or OSX, but I'm sure that someone here can state it. When started with a hard memory limit, Maple will stop when it reaches the limit, but I believe that saving the worksheet should then be OK. The key bit would be to make the hard limit be less then the total amount of physical RAM in your computer (not just less than the total amount of OS virtual memory).

As far as Matrices and LinearAlgebra goes, you made another post a short while back about being confused and frustrated with matrices, Matrices, <<>> notation, Matrix() the constructor, LinearAlgebra and LinearAlgebra[Generic]. I can offer this advice on that:

  • Avoid lowercase matrix, vector, and array. They are for the deprecated linalg package. Use uppercase Matrix and Vector.
  • The angle-bracket <<>> notation builds an uppercase Matrix, just like the Matrix() constructor routine does. Similarly for <> and Vector().
  • Don't load either of LinearAlgebra or LinearAlgebra[Generic] (using the `with` command) if you intend on using routines from each side by side. Instead use their long form names such as LinearAlgebra[MatrixAdd], etc, to keep it explicitly clear. Read their help-pages if you are unsure which package does what.

acer

You can right-click on a Windows launcher icon, click Properties and edit the Target field to include a -T switch (after the closing quotes).  For example, I changed the Target for Classic Worksheet Maple 12 to

"C:\Program Files\Maple 12\bin.win\cwmaple.exe"  -T100,100000

(i.e. 100 seconds, 100000 kB of memory).  I tried the command

> Q:= expand((a+b+c)^(10^8)):

and very soon I got a pop-up window

"Execution stopped: memory allocation failed.  Please see ?alloc for more detail"

According to the Task Manager, mserver.exe was using 404,784K at this point.
Further computation is of course impossible, but the worksheet can be saved, and mserver.exe is shut down successfully.

 

Also, during a Maple session, the memory used can be restricted using kernelopts(datalimit). When the limit is reached, the kernel shuts down, but the GUI works, and it is possible to save the worksheet(s). There is a help page about that, ?alloc

Alec