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

NAME

zung2l - generate an m by n complex matrix Q with orthonormal columns,

SYNOPSIS

  SUBROUTINE ZUNG2L( M, N, K, A, LDA, TAU, WORK, INFO)
  DOUBLE COMPLEX A(LDA,*), TAU(*), WORK(*)
  INTEGER M, N, K, LDA, INFO

  SUBROUTINE ZUNG2L_64( M, N, K, A, LDA, TAU, WORK, INFO)
  DOUBLE COMPLEX A(LDA,*), TAU(*), WORK(*)
  INTEGER*8 M, N, K, LDA, INFO

F95 INTERFACE

  SUBROUTINE UNG2L( M, [N], [K], A, [LDA], TAU, [WORK], [INFO])
  COMPLEX(8), DIMENSION(:) :: TAU, WORK
  COMPLEX(8), DIMENSION(:,:) :: A
  INTEGER :: M, N, K, LDA, INFO

  SUBROUTINE UNG2L_64( M, [N], [K], A, [LDA], TAU, [WORK], [INFO])
  COMPLEX(8), DIMENSION(:) :: TAU, WORK
  COMPLEX(8), DIMENSION(:,:) :: A
  INTEGER(8) :: M, N, K, LDA, INFO

C INTERFACE

#include <sunperf.h>

void zung2l(int m, int n, int k, doublecomplex *a, int lda, doublecomplex *tau, int *info);

void zung2l_64(long m, long n, long k, doublecomplex *a, long lda, doublecomplex *tau, long *info);

PURPOSE

zung2l L generates an m by n complex matrix Q with orthonormal columns, which is defined as the last n columns of a product of k elementary reflectors of order m

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

as returned by CGEQLF.

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

• WORK (workspace)
  dimension(N)

• INFO (output)
  

   = 0: successful exit

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