Previous: dlatzm Up: ../lapack-d.html Next: dlauum

NAME DLAUU2 - 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 DLAUU2( UPLO, N, A, LDA, INFO ) CHARACTER UPLO INTEGER INFO, LDA, N DOUBLE PRECISION A( LDA, * ) PURPOSE DLAUU2 computes the product U * U' or L' * L, where the tri- angular factor U or L is stored in the upper or lower tri- angular 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 unblocked form of the algorithm, calling Level 2 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) DOUBLE PRECISION 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