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

NAME

cungr2 - generate an m by n complex matrix Q with orthonormal rows,

SYNOPSIS

  SUBROUTINE CUNGR2( M, N, K, A, LDA, TAU, WORK, INFO)
  COMPLEX A(LDA,*), TAU(*), WORK(*)
  INTEGER M, N, K, LDA, INFO

  SUBROUTINE CUNGR2_64( M, N, K, A, LDA, TAU, WORK, INFO)
  COMPLEX A(LDA,*), TAU(*), WORK(*)
  INTEGER*8 M, N, K, LDA, INFO

F95 INTERFACE

  SUBROUTINE UNGR2( [M], [N], [K], A, [LDA], TAU, [WORK], [INFO])
  COMPLEX, DIMENSION(:) :: TAU, WORK
  COMPLEX, DIMENSION(:,:) :: A
  INTEGER :: M, N, K, LDA, INFO

  SUBROUTINE UNGR2_64( [M], [N], [K], A, [LDA], TAU, [WORK], [INFO])
  COMPLEX, DIMENSION(:) :: TAU, WORK
  COMPLEX, DIMENSION(:,:) :: A
  INTEGER(8) :: M, N, K, LDA, INFO

C INTERFACE

#include <sunperf.h>

void cungr2(int m, int n, int k, complex *a, int lda, complex *tau, int *info);

void cungr2_64(long m, long n, long k, complex *a, long lda, complex *tau, long *info);

PURPOSE

cungr2 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)
  dimension(M)

• INFO (output)
  

   = 0: successful exit

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