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# 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

### See Also

- 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

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