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

NAME

dormqr - overwrite the general real M-by-N matrix C with SIDE = 'L' SIDE = 'R' TRANS = 'N'

SYNOPSIS

  SUBROUTINE DORMQR( SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, 
 *      LWORK, INFO)
  CHARACTER * 1 TRANS
  INTEGER M, N, K, LDA, LDC, LWORK, INFO
  DOUBLE PRECISION A(LDA,*), TAU(*), C(LDC,*), WORK(*)
   SIDE

  SUBROUTINE DORMQR_64( SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, 
 *      WORK, LWORK, INFO)
  CHARACTER * 1 TRANS
  INTEGER*8 M, N, K, LDA, LDC, LWORK, INFO
  DOUBLE PRECISION A(LDA,*), TAU(*), C(LDC,*), WORK(*)
   SIDE

F95 INTERFACE

  SUBROUTINE ORMQR( SIDE, [TRANS], [M], [N], [K], A, [LDA], TAU, C, 
 *       [LDC], [WORK], [LWORK], [INFO])
  CHARACTER(LEN=1) :: TRANS
  INTEGER :: M, N, K, LDA, LDC, LWORK, INFO
  REAL(8), DIMENSION(:) :: TAU, WORK
  REAL(8), DIMENSION(:,:) :: A, C
   :: SIDE

  SUBROUTINE ORMQR_64( SIDE, [TRANS], [M], [N], [K], A, [LDA], TAU, C, 
 *       [LDC], [WORK], [LWORK], [INFO])
  CHARACTER(LEN=1) :: TRANS
  INTEGER(8) :: M, N, K, LDA, LDC, LWORK, INFO
  REAL(8), DIMENSION(:) :: TAU, WORK
  REAL(8), DIMENSION(:,:) :: A, C
   :: SIDE

C INTERFACE

#include <sunperf.h>

void dormqr( side, char trans, int m, int n, int k, double *a, int lda, double *tau, double *c, int ldc, int *info);

void dormqr_64( side, char trans, long m, long n, long k, double *a, long lda, double *tau, double *c, long ldc, long *info);

PURPOSE

dormqr overwrites the general real M-by-N matrix C with TRANS = 'T': Q**T * C C * Q**T

where Q is a real orthogonal matrix defined as the product of k elementary reflectors

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

as returned by SGEQRF. Q is of order M if SIDE = 'L' and of order N if SIDE = 'R'.

ARGUMENTS

• SIDE (input)
  

   = 'L': apply Q or Q**T from the Left;

   = 'R': apply Q or Q**T from the Right.

• TRANS (input)
  

   = 'N':  No transpose, apply Q;

   = 'T':  Transpose, apply Q**T.

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

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

• K (input)
  The number of elementary reflectors whose product defines the matrix Q. If SIDE = 'L', M > = K > = 0; if SIDE = 'R', N > = K > = 0.

• A (input)
  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. A is modified by the routine but restored on exit.

• LDA (input)
  The leading dimension of the array A. If SIDE = 'L', LDA > = max(1,M); if SIDE = 'R', LDA > = max(1,N).

• TAU (input)
  TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGEQRF.

• C (input/output)
  On entry, the M-by-N matrix C. On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q.

• LDC (input)
  The leading dimension of the array C. LDC > = max(1,M).

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

• LWORK (input)
  The dimension of the array WORK. If SIDE = 'L', LWORK > = max(1,N); if SIDE = 'R', LWORK > = max(1,M). For optimum performance LWORK > = N*NB if SIDE = 'L', and LWORK > = M*NB if SIDE = 'R', where NB is the optimal blocksize.

  If LWORK = -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 LWORK is issued by XERBLA.

• INFO (output)
  

   = 0:  successful exit

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