luigidavinci

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12 years, 148 days

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These are questions asked by luigidavinci

Hi there,

 I have a piece of code that uses lists instead of vectors and recently, it crashed, it ran out of memory. Long story short, if I use vectors instead of lists, the performance is much better and optimal (this I knew but I was lazy to translate all my code). However, there's one single line that I cannot efficiently translate and it's the one that uses the function member(). Before, I had the following (it's an oversimplification of my code in order to easily discuss it in here):

I think I have come across with what it looks like a very basic bug using the member function. I get the error message: "Error, cannot determine if this expression is true or false: (3) < 100"  after the execution of the last line to the next code:

>Test:=Array(1..3,[1,2,3]);
>member(3,Test,'l');
>if l<100 then print("yes"); end if;

am I doing something wrong ?? I even checked the type of the variable 'l' and it is indeed an integer...

Hi everybody, I have a rather large code in Maple for my research which needs fast eigensolving for large sparse matrices, thus, I am using the Matlab link to parse my matrices and get them eigensolved in Matlab. The problem is that, I am unable to directly parse a Maple sparse matrix to a Matlab sparse matrix which substantially slows down the calculation.

This is the best I can do so far:

 

> H:=Matrix(5000,5000,shape=symmetric,storage=sparse,datatype=float[8]):

I am dissapointed. I recently upgraded to Maple 15 and I bought a license for the NAG libraries thinking that I could use NAG mark 8 chapter F12 to solve my Eigenvalue problem with large sparse matrix, in reality, there seems to be no implementation of these NAG routines in Maple. is there a way to get around this problem? I know I can also connect to MATLAB to take advantage of the integrated sparse handling but I want to avoid buying another piece of software(you know we scientist aren't millionaries).

Hi there. I have two expressions of type Matrix(7x1), one I entered directly and the other one is the result of a  procedure calling. They only differ by the term [1,1], so when I do a comparation of the appropiate submatrix using Equal I get a positive answer:

 

>Equal(SubMatrix(atataaV(1,1,1,1,u1),2..-1,1),SubMatrix(u1,2..-1,1));

true

 

Now, the elements of the submatrices depend on the symbol 'n',...

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