Solve Ax=b with LU factorization

2017 9 11
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更新时间：2017 9 11
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I'm trying to solve A*x = b with LU decomposition and back substitution. Where x is the unknown vector.
A =
350 0 0 0 0
-1 0 0 0 0.0091
5 0 0 0 0
0.0095 0 0 0 1
0 -1 0 0 0.0091
b =
1
0
2
1
But I always end up with: Matrix is singular to working precision
Hope someone can provide me with a working code.

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John D'Errico
John D'Errico 2017-9-11
编辑：John D'Errico 2017-9-11

0 个投票

The matrix is singular! Hint: read the error message. There is no solution.
Worse, there could NEVER be a solution, even if the matrix was not singular!!!!!!!
A is a 5x5 matrix. b is a 4x1 vector.
There exists no possible vector x such that A*x will be a 4x1 vector. NOT gonna happen. EVER. So asking for working code to do the impossible is a waste of CPU cycles. Trying to do that with a singular matrix? Even sillier.

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