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Dan Maynard - Problem with solving matrices

Dan Maynard - Problem with solving matrices

by Arnold Pizer -
Number of replies: 0
inactiveTopicProblem with solving matrices topic started 7/16/2002; 9:34:23 AM
last post 7/19/2002; 7:54:18 AM
userDan Maynard - Problem with solving matrices  blueArrow
7/16/2002; 9:34:23 AM (reads: 4673, responses: 1)
I am wiritng problems to solve matrices. The solve_LR function correctly works sometimes, but on specific matrices it returns no solution when there definitely is a solution (so far it has only happened when there are all zeros in the last column). Has anyone else had this problem with the function, or does anyone know of any bugs (and hopefully fixes) with the LR_matrix->solve_LR command? Thanks.

Dan

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userMichael Gage - Re: Problem with solving matrices  blueArrow
7/19/2002; 7:54:18 AM (reads: 5604, responses: 0)
The original docs for the MatrixReal.pm module, taken from CPAN, are at

http://webhost.math.rochester.edu/webworkdocs/docs/pglanguage/pod/matrix . Search for matrix->solve to see an example of using the solve method.

I am not aware of any bugs in this method (although I know that it doesn't always work with complex numbers). Could you post one or two of your specific examples that don't work?

All zeros in the last column indicate that the matrix is singular. Solutions will exist only for vectors lying in the span of the first columns of the matrix. Could that be the problem for the examples? Also double check that you and the program have rows and columns (and/or left or right multiplication) in sync with each other. These are the only two ideas that occur to me right away.

I'll be away again for the next two weeks so I won't be able to troubleshoot further until the first week in August, but perhaps other readers can identify the problem.

-- Mike.

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