— Loadable Function: [x, rcond] = spinv (a, Q)

Compute the inverse of the sparse square matrix a. Return an estimate of the reciprocal condition number if requested, otherwise warn of an ill-conditioned matrix if the reciprocal condition number is small. This function takes advantage of the sparsity of the matrix to accelerate the calculation of the inverse.

In general x will be a full matrix, and so if possible forming the inverse of a sparse matrix should be avoided. It is significantly more accurate and faster to do y = a \ b, rather than y = spinv (a) * b.