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Symbolic matrix inverse takes long time

Leo Murphy
Posted 8 months ago

Hi hope you are all doing well, It's my first time working with matrix in Mathematica so I want to calculate the inverse of the matrix "g" and multiply it by "G" and plot this result, can you confirm if I done it the correct way because the calculus take time and I don't know if its correct or not, Thank you all in advance.

POSTED BY: Leo Murphy
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It appears to be badly conditioned though. Whether that's a problem is likely to be application dependent.
POSTED BY: Daniel Lichtblau

You may try with high precision arithmetic, something like this:

b = Inverse[N[g, 100]];
POSTED BY: Gianluca Gorni
Leo Murphy
Leo Murphy
Posted 8 months ago

Yeah I actually thought of discretisizing the expressions of "g" and "G", the problem is the only way to solve this is by a matrix form because its a Freedholm equation
POSTED BY: Leo Murphy

The matrix g is 100x100 and symbolic. Do you really expect to get a symbolic inverse? I tried with the 8x8 case and the determinant of g takes 400 megabytes of memory.

You can try numericizing g, but it turns out that it is badly conditioned for the inverse.

Instead of inverting the full matrix, you may try solving the system g.x=G.
POSTED BY: Gianluca Gorni
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