lapack中cgesv的“信息> 0”错误到底是什么？

Question

I'm trying to use lapack to solve a set linear equations, but when I run the program I get an error which is info > 0. It states that

Element U(10011001) is exactly zero. The factorization has been completed, but the factor U is exactly singular, so the solution could not be computed.'

What does this exactly mean? I'm using the cgesv subroutine. I have a 1001 by 1001 matrix for A and B and X are 1001 by 1. What does the "info > 0 error" actually mean in simple terms?

Answer 1

It means that your coefficient matrix is not invertible and the solution is not found. The error comes from the initial LU factorization of the coefficient matrix. And the last diagonal element of U turns out to be zero.