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

NAME

zungqr - generate an M-by-N complex matrix Q with orthonormal columns,

SYNOPSIS

  SUBROUTINE ZUNGQR( M, N, K, A, LDA, TAU, WORKIN, LWORKIN, INFO)
  DOUBLE COMPLEX A(LDA,*), TAU(*), WORKIN(*)
  INTEGER M, N, K, LDA, LWORKIN, INFO

  SUBROUTINE ZUNGQR_64( M, N, K, A, LDA, TAU, WORKIN, LWORKIN, INFO)
  DOUBLE COMPLEX A(LDA,*), TAU(*), WORKIN(*)
  INTEGER*8 M, N, K, LDA, LWORKIN, INFO

F95 INTERFACE

  SUBROUTINE UNGQR( M, [N], [K], A, [LDA], TAU, [WORKIN], [LWORKIN], 
 *       [INFO])
  COMPLEX(8), DIMENSION(:) :: TAU, WORKIN
  COMPLEX(8), DIMENSION(:,:) :: A
  INTEGER :: M, N, K, LDA, LWORKIN, INFO

  SUBROUTINE UNGQR_64( M, [N], [K], A, [LDA], TAU, [WORKIN], [LWORKIN], 
 *       [INFO])
  COMPLEX(8), DIMENSION(:) :: TAU, WORKIN
  COMPLEX(8), DIMENSION(:,:) :: A
  INTEGER(8) :: M, N, K, LDA, LWORKIN, INFO

C INTERFACE

#include <sunperf.h>

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

void zungqr_64(long m, long n, long k, doublecomplex *a, long lda, doublecomplex *tau, long *info);

PURPOSE

zungqr generates an M-by-N complex matrix Q with orthonormal columns, which is defined as the first N columns of a product of K elementary reflectors of order M

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

as returned by CGEQRF.

ARGUMENTS

• M (input)
  The number of rows of the matrix Q. M > = 0.

• N (input)
  The number of columns of the matrix Q. M > = N > = 0.

• K (input)
  The number of elementary reflectors whose product defines the matrix Q. N > = K > = 0.

• A (input/output)
  On entry, the i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by CGEQRF in the first k columns 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 CGEQRF.

• WORKIN (workspace)
  On exit, if INFO = 0, WORKIN(1) returns the optimal LWORKIN.

• LWORKIN (input)
  The dimension of the array WORKIN. LWORKIN > = max(1,N). For optimum performance LWORKIN > = N*NB, where NB is the optimal blocksize.

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

• INFO (output)
  

   = 0:  successful exit

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