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These are questions asked by sand15


This sequence of commands works perfectly well

     plotsetup(jpeg, plotoutput=SomeJpegFile);
     plot(x, x=0..1);

Why this one doesn't create the file SomeJpegFile ?

f := proc()
     plotsetup(jpeg, plotoutput=SomeJpegFile);
     plot(x, x=0..1);
end proc;


Thanks in advance



I use Statistics[Biplot] and the rendering is very bad with those huge arrows.

For the moment I fix this by modifying the definitions of the curves which draw each arrow (after using getdata to recover the Biplot structure)

Does it exist a simpler way to manage the appearance of the arrows ?
(options cb, cw and ch of plottols[arrow] are incorrect in Statistics[Biplot](..., arrow=[...]).

Thanks in advance


Could you please help me in solving this problem ?

  • N is the number of row, about 10^4 in real applications
  • P is the number of columns (about 5)
  • A and B are two NxP matrices
  • C is the Nx(2P) matrix defined by
    • its 2*k-1 th column is the k th column of A
    • its 2*k th column is the k th column of B

What is the fastest and less memory consumming way to construct this matrix C ?

Thanks in advance




As a notional example those instructions generate 21 variables and around 4 Giga Bytes of data (bottom right of the Maple window ; roughly the same value read from the windows manager)

for n from 1 to 10 do
   X__||n := RandomVariable(Uniform(0,1)):
   S__||n := Sample(X__||n, 10^8)
end do:

I want to clean some part of the  memory ; for instance all the S__||n.
The following doesn't work

KeepVars := { seq(X__||n, n=1..10)}:
unassign({anames(user)} minus KeepVars ) ;

Is there a way to deallocate the memory occupied by some of my user variables ?

Hi there,

The command

           dsolve(MyOde, numeric, range=MyRange, method=rosenbrock, output=piecewise)

returns a list of solution pieces which is not sufficiently dense according to how I intend to use it.

Is there a possibility to impose the "number of pieces" or the positions of the "breaks" in this command ?

Thanks in advance for any suggestion.


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