man slauum (Fonctions bibliothèques) - compute the product U * U' or L' * L, where the triangular factor U or L is stored in the upper or lower triangular part of the array A
NAME
SLAUUM - compute the product U * U' or L' * L, where the triangular factor U or L is stored in the upper or lower triangular part of the array A
SYNOPSIS
- SUBROUTINE SLAUUM(
- UPLO, N, A, LDA, INFO )
- CHARACTER UPLO
- INTEGER INFO, LDA, N
- REAL A( LDA, * )
PURPOSE
SLAUUM computes the product U * U' or L' * L, where the triangular factor U or L is stored in the upper or lower triangular part of the array A.
If UPLO = 'U' or 'u' then the upper triangle of the result is stored,
overwriting the factor U in A.
If UPLO = 'L' or 'l' then the lower triangle of the result is stored,
overwriting the factor L in A.
This is the blocked form of the algorithm, calling Level 3 BLAS.
ARGUMENTS
- UPLO (input) CHARACTER*1
- Specifies whether the triangular factor stored in the array A
is upper or lower triangular:
= 'U': Upper triangular
= 'L': Lower triangular - N (input) INTEGER
- The order of the triangular factor U or L. N >= 0.
- A (input/output) REAL array, dimension (LDA,N)
- On entry, the triangular factor U or L. On exit, if UPLO = 'U', the upper triangle of A is overwritten with the upper triangle of the product U * U'; if UPLO = 'L', the lower triangle of A is overwritten with the lower triangle of the product L' * L.
- LDA (input) INTEGER
- The leading dimension of the array A. LDA >= max(1,N).
- INFO (output) INTEGER
- = 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value