Function

NumCosmoMathlapack_dsytrs

Declaration [src]

gint
ncm_lapack_dsytrs (
  gchar uplo,
  gint n,
  gint nrhs,
  gdouble* a,
  gint lda,
  gint* ipiv,
  gdouble* b,
  gint ldb
)

Description [src]

This function computes the solution of $A X = B$ for a real symmetric positive definite matrix a = A using the Cholesky factorization $A = U^TU$ or $A = LL^T$ already performed by ncm_lapack_dpotrf(). On entry b contain the vectors $B$ and on exit b contain the solutions if the return is 0.

Parameters

uplo

Type: gchar

‘U’ upper triangle of a is stored; ‘L’ lower triangle of a is stored.

n

Type: gint

The order of the matrix a, n >= 0.

nrhs

Type: gint

Number of right-hand-side vectors to solve.

a

Type: gdouble*

Array of doubles with dimension (n, lda).

The data is owned by the caller of the function.

lda

Type: gint

The leading dimension of the array a, lda >= max (1, n).

ipiv

Type: gint*

Information about decomposition swaps and blocks.

The data is owned by the caller of the function.

b

Type: gdouble*

Array of doubles with dimension (n, ldb).

The data is owned by the caller of the function.

ldb

Type: gint

The leading dimension of the array b, ldb >= max (1, n).

Return value

Type: gint

I = 0: successful exit

     < 0:  -i, the i-th argument had an illegal value

     > 0: the (i,i) element of the factor U
       or L is zero, and the inverse could not be computed.