taucs_chinfo

get information on Cholesky factors

Calling Sequence

[OK, n, cnz] = taucs_chinfo(C_ptr)

Arguments

:C_ptr a pointer to a Cholesky factorization : :OK a scalar boolean : :n a scalar integer : :cnz a scalar integer :

Description

This function may be used to know basic information about the Cholesky factor created with taucs_chfact :

• first OK is %t if C_ptr is a valid pointer to an Cholesky factorization (and %f else)
• if OK is %t then n and cnz are respectively the matrix order and the number of non zeros elements in the supernodal structure storing C ; if OK is %f, n and cnz are set to the void matrix [].

Details

Due to the supernodal structure used for C, cnz is larger than the exact number of non-zeros elements in C (and so this cnz is a mesure of the memory used internally). To get the exact cnz you may retrieve the Cholesky factor with taucs_chget then apply the nnz scilab function (see the 2d example in taucs_chget).

See Also

• taucs_chfact cholesky factorisation of a sparse s.p.d. matrix
• taucs_chsolve solve a linear sparse (s.p.d.) system given the Cholesky factors
• taucs_chdel utility function used with taucs_chfact
• taucs_chget retrieve the Cholesky factorization at the scilab level