• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

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

SYNOPSIS

  SUBROUTINE ZUNGLQ( M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
  DOUBLE COMPLEX A(LDA,*), TAU(*), WORK(*)
  INTEGER M, N, K, LDA, LWORK, INFO

  SUBROUTINE ZUNGLQ_64( M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
  DOUBLE COMPLEX A(LDA,*), TAU(*), WORK(*)
  INTEGER*8 M, N, K, LDA, LWORK, INFO

F95 INTERFACE

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

  SUBROUTINE UNGLQ_64( M, [N], [K], A, [LDA], TAU, [WORK], [LWORK], 
 *       [INFO])
  COMPLEX(8), DIMENSION(:) :: TAU, WORK
  COMPLEX(8), DIMENSION(:,:) :: A
  INTEGER(8) :: M, N, K, LDA, LWORK, INFO

C INTERFACE

#include <sunperf.h>

void zunglq(int m, int n, int k, doublecomplex *a, int lda, doublecomplex *tau, int *info);

void zunglq_64(long m, long n, long k, doublecomplex *a, long lda, doublecomplex *tau, long *info);

PURPOSE

zunglq generates an M-by-N complex 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 CGELQF.

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 CGELQF 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 CGELQF.

• 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)
  

   = 0:  successful exit;

   < 0:  if INFO  = -i, the i-th argument has an illegal value