taucs_chinfo — get information on Cholesky factors
[OK, n, cnz] = taucs_chinfo(C_ptr)
a pointer to a Cholesky factorization
a scalar boolean
a scalar integer
a scalar integer
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 [].
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).