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See the recommended documentation of this function

Aide Scilab >> Interface avec UMFPACK (sparse) > taucs_chsolve

# taucs_chsolve

solve a linear sparse (s.p.d.) system given the Cholesky factors

### Calling Sequence

`[x] = taucs_chsolve(C_ptr, b [, A])`

### Arguments

C_ptr

a pointer to a handle of the Cholesky factors (C,p with A(p,p)=CC')

b

a real column vector or a matrix (multiple rhs)

x

a real column vector or a matrix in case of multiple rhs ( x(:,i) is solution of A x(:,i) = b(:,i))

A

(optional) the real s.p.d. matrix A (to use for iterative refinement step)

### Description

This function must be used in conjonction with taucs_chfact which computes the Cholesky factorization of a sparse real s.p.d. matrix. When the matrix `A` is provided, one iterative refinement step is done (the refined solution is accepted if it improves the 2-norm of the residual `Ax-b`).

Like in taucs_chfact the matrix A may be provided either in its complete form (that is with the lower triangle also) or only with its upper triangle.

### Examples

see the example section of taucs_chfact

• taucs_chfact — cholesky factorisation of a sparse s.p.d. matrix
• taucs_chdel — utility function used with taucs_chfact
• taucs_chinfo — get information on Cholesky factors
• taucs_chget — retrieve the Cholesky factorization at the scilab level
• cond2sp — computes an approximation of the 2-norm condition number of a s.p.d. sparse matrix

### Authors

• taucs by Sivan Toledo (see taucs_license)
• scilab interface by Bruno Pincon