dorgl2

NAME

dorgl2 - generate an m by n real matrix Q with orthonormal rows,

SYNOPSIS

  SUBROUTINE DORGL2( M, N, K, A, LDA, TAU, WORK, INFO)
  INTEGER M, N, K, LDA, INFO
  DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)
 
  SUBROUTINE DORGL2_64( M, N, K, A, LDA, TAU, WORK, INFO)
  INTEGER*8 M, N, K, LDA, INFO
  DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)

F95 INTERFACE

  SUBROUTINE ORGL2( [M], [N], [K], A, [LDA], TAU, [WORK], [INFO])
  INTEGER :: M, N, K, LDA, INFO
  REAL(8), DIMENSION(:) :: TAU, WORK
  REAL(8), DIMENSION(:,:) :: A
 
  SUBROUTINE ORGL2_64( [M], [N], [K], A, [LDA], TAU, [WORK], [INFO])
  INTEGER(8) :: M, N, K, LDA, INFO
  REAL(8), DIMENSION(:) :: TAU, WORK
  REAL(8), DIMENSION(:,:) :: A

C INTERFACE

#include <sunperf.h>

void dorgl2(int m, int n, int k, double *a, int lda, double *tau, int *info);

void dorgl2_64(long m, long n, long k, double *a, long lda, double *tau, long *info);

PURPOSE

dorgl2 generates an m by n real matrix Q with orthonormal rows, which is defined as the first m rows of a product of k elementary reflectors of order n

      Q  =  H(k) . . . H(2) H(1)

as returned by SGELQF.

ARGUMENTS

* M (input): The number of rows of the matrix Q. M >= 0.
* N (input): The number of columns of the matrix Q. N >= M.
* K (input): The number of elementary reflectors whose product defines the matrix Q. M >= K >= 0.
* A (input/output): On entry, the i-th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by SGELQF in the first k rows of its array argument A. On exit, the m-by-n matrix Q.
* LDA (input): The first dimension of the array A. LDA >= max(1,M).
* TAU (input): TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGELQF.
* WORK (workspace): dimension(M)
* INFO (output)