NAME¶

DLAUU2 - 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

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 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 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