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

NAME

sorgqr - generate an M-by-N real matrix Q with orthonormal columns,

SYNOPSIS

  SUBROUTINE SORGQR( M, N, K, A, LDA, TAU, WORK, LDWORK, INFO)
  INTEGER M, N, K, LDA, LDWORK, INFO
  REAL A(LDA,*), TAU(*), WORK(*)

  SUBROUTINE SORGQR_64( M, N, K, A, LDA, TAU, WORK, LDWORK, INFO)
  INTEGER*8 M, N, K, LDA, LDWORK, INFO
  REAL A(LDA,*), TAU(*), WORK(*)

F95 INTERFACE

  SUBROUTINE ORGQR( M, [N], [K], A, [LDA], TAU, [WORK], [LDWORK], 
 *       [INFO])
  INTEGER :: M, N, K, LDA, LDWORK, INFO
  REAL, DIMENSION(:) :: TAU, WORK
  REAL, DIMENSION(:,:) :: A

  SUBROUTINE ORGQR_64( M, [N], [K], A, [LDA], TAU, [WORK], [LDWORK], 
 *       [INFO])
  INTEGER(8) :: M, N, K, LDA, LDWORK, INFO
  REAL, DIMENSION(:) :: TAU, WORK
  REAL, DIMENSION(:,:) :: A

C INTERFACE

#include <sunperf.h>

void sorgqr(int m, int n, int k, float *a, int lda, float *tau, int *info);

void sorgqr_64(long m, long n, long k, float *a, long lda, float *tau, long *info);

PURPOSE

sorgqr generates an M-by-N real 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 SGEQRF.

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 SGEQRF 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 SGEQRF.

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

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

  If LDWORK = -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 LDWORK is issued by XERBLA.

• INFO (output)
  

   = 0:  successful exit

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