cungrq

NAME

cungrq - generate an M-by-N complex matrix Q with orthonormal rows,

SYNOPSIS

  SUBROUTINE CUNGRQ( M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
  COMPLEX A(LDA,*), TAU(*), WORK(*)
  INTEGER M, N, K, LDA, LWORK, INFO
 
  SUBROUTINE CUNGRQ_64( M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
  COMPLEX A(LDA,*), TAU(*), WORK(*)
  INTEGER*8 M, N, K, LDA, LWORK, INFO

F95 INTERFACE

  SUBROUTINE UNGRQ( M, [N], [K], A, [LDA], TAU, [WORK], [LWORK], [INFO])
  COMPLEX, DIMENSION(:) :: TAU, WORK
  COMPLEX, DIMENSION(:,:) :: A
  INTEGER :: M, N, K, LDA, LWORK, INFO
 
  SUBROUTINE UNGRQ_64( M, [N], [K], A, [LDA], TAU, [WORK], [LWORK], 
 *       [INFO])
  COMPLEX, DIMENSION(:) :: TAU, WORK
  COMPLEX, DIMENSION(:,:) :: A
  INTEGER(8) :: M, N, K, LDA, LWORK, INFO

C INTERFACE

#include <sunperf.h>

void cungrq(int m, int n, int k, complex *a, int lda, complex *tau, int *info);

void cungrq_64(long m, long n, long k, complex *a, long lda, complex *tau, long *info);

PURPOSE

cungrq generates an M-by-N complex 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 CGERQF.

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 CGERQF 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 CGERQF.

* WORK (workspace)

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

* LWORK (input)

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

If LWORK = -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 LWORK is issued by XERBLA.

* INFO (output)