sorgrq

NAME

sorgrq - generate an M-by-N real matrix Q with orthonormal rows,

SYNOPSIS

  SUBROUTINE SORGRQ( M, N, K, A, LDA, TAU, WORK, LDWORK, INFO)
  INTEGER M, N, K, LDA, LDWORK, INFO
  REAL A(LDA,*), TAU(*), WORK(*)
 
  SUBROUTINE SORGRQ_64( M, N, K, A, LDA, TAU, WORK, LDWORK, INFO)
  INTEGER*8 M, N, K, LDA, LDWORK, INFO
  REAL A(LDA,*), TAU(*), WORK(*)

F95 INTERFACE

  SUBROUTINE ORGRQ( M, [N], [K], A, [LDA], TAU, [WORK], [LDWORK], 
 *       [INFO])
  INTEGER :: M, N, K, LDA, LDWORK, INFO
  REAL, DIMENSION(:) :: TAU, WORK
  REAL, DIMENSION(:,:) :: A
 
  SUBROUTINE ORGRQ_64( M, [N], [K], A, [LDA], TAU, [WORK], [LDWORK], 
 *       [INFO])
  INTEGER(8) :: M, N, K, LDA, LDWORK, INFO
  REAL, DIMENSION(:) :: TAU, WORK
  REAL, DIMENSION(:,:) :: A

C INTERFACE

#include <sunperf.h>

void sorgrq(int m, int n, int k, float *a, int lda, float *tau, int *info);

void sorgrq_64(long m, long n, long k, float *a, long lda, float *tau, long *info);

PURPOSE

sorgrq generates an M-by-N real matrix Q with orthonormal rows, which is defined as the last M rows of a product of K elementary reflectors of order N

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

as returned by SGERQF.

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 (m-k+i)-th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by SGERQF in the last 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 SGERQF.

* WORK (workspace)

On exit, if INFO = 0, WORK(1) returns the optimal LDWORK.

* LDWORK (input)

The dimension of the array WORK. LDWORK >= max(1,M). For optimum performance LDWORK >= M*NB, where NB is the optimal blocksize.

If LDWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LDWORK is issued by XERBLA.

* INFO (output)