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matrices.c: 0 not ignored when inverting diagonals in pseudoinverse #52

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stonemaguire opened this issue Jul 6, 2023 · 0 comments · May be fixed by #57
Open

matrices.c: 0 not ignored when inverting diagonals in pseudoinverse #52

stonemaguire opened this issue Jul 6, 2023 · 0 comments · May be fixed by #57

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@stonemaguire
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zscilib/src/matrices.c

Lines 1785 to 1791 in 34c3432

/* Invert the diagonal values in 'e'. If a value is zero, do
* nothing to it. */
zsl_mtx_get(&e, g, g, &x);
if ((x < epsilon) || (x > -epsilon)) {
x = 1 / x;
zsl_mtx_set(&e, g, g, x);
}

In the if statement on line 1788, x > -epsilon always evaluates to true when x is 0 because epsilon is equal to 1e-6 and 0 is always bigger than -1e-6. This causes an incorrect output matrix with infinity values since 0 should be ignored.

I changed line 1788 to the below code to fix this issue:
if (((x < epsilon) || (x > -epsilon)) && x != 0) {
@stonemaguire stonemaguire linked a pull request Jan 17, 2024 that will close this issue
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Fixes pseudoinverse of matrix in matrices.c stonemaguire/zscilib
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@stonemaguire