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

NAME

dorgr2 - generate an m by n real matrix Q with orthonormal rows,

SYNOPSIS

  SUBROUTINE DORGR2( M, N, K, A, LDA, TAU, WORK, INFO)
  INTEGER M, N, K, LDA, INFO
  DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)

  SUBROUTINE DORGR2_64( M, N, K, A, LDA, TAU, WORK, INFO)
  INTEGER*8 M, N, K, LDA, INFO
  DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)

F95 INTERFACE

  SUBROUTINE ORGR2( [M], [N], [K], A, [LDA], TAU, [WORK], [INFO])
  INTEGER :: M, N, K, LDA, INFO
  REAL(8), DIMENSION(:) :: TAU, WORK
  REAL(8), DIMENSION(:,:) :: A

  SUBROUTINE ORGR2_64( [M], [N], [K], A, [LDA], TAU, [WORK], [INFO])
  INTEGER(8) :: M, N, K, LDA, INFO
  REAL(8), DIMENSION(:) :: TAU, WORK
  REAL(8), DIMENSION(:,:) :: A

C INTERFACE

#include <sunperf.h>

void dorgr2(int m, int n, int k, double *a, int lda, double *tau, int *info);

void dorgr2_64(long m, long n, long k, double *a, long lda, double *tau, long *info);

PURPOSE

dorgr2 generates an m by n real 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 SGERQF.

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 SGERQF 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 SGERQF.

• WORK (workspace)
  dimension(M)

• INFO (output)
  

   = 0: successful exit

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