---
name: "clauum"
section: "3lapack"
platform: "linux"
package: "liblapack-doc"
version: "3.2.1-8"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/clauum/3lapack"
---

# clauum(3lapack)

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

## NAME

CLAUUM - 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 CLAUUM(

  UPLO, N, A, LDA, INFO )

- CHARACTER

  UPLO

- INTEGER

  INFO, LDA, N

- COMPLEX

  A( LDA, \* )

## PURPOSE

CLAUUM 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) COMPLEX 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