Question

I’m working with 6×6 matrices which have varying precisions of data. When I try to inverse that matrix in MATLAB I usually get Inf or NaN as all the data and MATLAB throws a warning:

Matrix is singular to working precision.

Is there anyway to avoid it and get proper results?

Answer 1

Your matrix seems to be rank deficient. Only full rank matrices can be robustly inverted.
You may circumvent your problem by adding a small identity matrix to the original one.

 A = rand(6,5);
 A = A*A'; %' symmetric rank 5 matrix
 iA = inv(A); % results with NaNs and infs A is singular
 iAs = inv( A + eye(6)*1e-3 ); % add small (1e-3) elements to diagonal - this should help