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 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

SunSoft, Inc.  —  Last change: 27 Jun 1995