MATLAB: Solve Ax=b with LU factorization

lu decompositionmatricesnumerical analyses

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.

Best Answer

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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