dlauum(3)

NAME

DLAUUM - compute the product U * U' or L' * L, where the

triangular factor U or L is stored in the upper or lower triangu

lar part of the array A

SYNOPSIS

SUBROUTINE DLAUUM( UPLO, N, A, LDA, INFO )
    CHARACTER      UPLO
    INTEGER        INFO, LDA, N
    DOUBLE         PRECISION A( LDA, * )

PURPOSE

DLAUUM computes the product U * U' or L' * L, where the

triangular factor U or L is stored in the upper or lower triangu

lar 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) 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 prod

uct 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 ille

gal value

LAPACK version 3.0 15 June 2000

DLAUUM(3)