##### 22.6.2.21 spchol

— Loadable Function: r = spchol (a)
— Loadable Function: [r, p] = spchol (a)
— Loadable Function: [r, p, q] = spchol (a)

> Compute the Cholesky factor, r, of the symmetric positive definite sparse matrix a, where

>               r' * r = a.

> If called with 2 or more outputs p is the 0 when r is positive definite and p is a positive integer otherwise.

> If called with 3 outputs then a sparsity preserving row/column permutation is applied to a prior to the factorization. That is r is the factorization of a`(`q`,`q`)` such that

>               r' * r = q * a * q'.

> Note that `splchol` factorizations is faster and use less memory.

> See also: spcholinv, spchol2inv, splchol.