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

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

Authors

  • taucs by Sivan Toledo (see taucs_license)
  • scilab interface by Bruno Pincon
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Last updated:
Wed Oct 05 12:10:58 CEST 2011