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

NAME

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

SYNOPSIS

  SUBROUTINE DOPMTR( SIDE, UPLO, TRANS, M, N, AP, TAU, C, LDC, WORK, 
 *      INFO)
  CHARACTER * 1 SIDE, UPLO, TRANS
  INTEGER M, N, LDC, INFO
  DOUBLE PRECISION AP(*), TAU(*), C(LDC,*), WORK(*)

  SUBROUTINE DOPMTR_64( SIDE, UPLO, TRANS, M, N, AP, TAU, C, LDC, 
 *      WORK, INFO)
  CHARACTER * 1 SIDE, UPLO, TRANS
  INTEGER*8 M, N, LDC, INFO
  DOUBLE PRECISION AP(*), TAU(*), C(LDC,*), WORK(*)

F95 INTERFACE

  SUBROUTINE OPMTR( SIDE, UPLO, [TRANS], [M], [N], AP, TAU, C, [LDC], 
 *       [WORK], [INFO])
  CHARACTER(LEN=1) :: SIDE, UPLO, TRANS
  INTEGER :: M, N, LDC, INFO
  REAL(8), DIMENSION(:) :: AP, TAU, WORK
  REAL(8), DIMENSION(:,:) :: C

  SUBROUTINE OPMTR_64( SIDE, UPLO, [TRANS], [M], [N], AP, TAU, C, [LDC], 
 *       [WORK], [INFO])
  CHARACTER(LEN=1) :: SIDE, UPLO, TRANS
  INTEGER(8) :: M, N, LDC, INFO
  REAL(8), DIMENSION(:) :: AP, TAU, WORK
  REAL(8), DIMENSION(:,:) :: C

C INTERFACE

#include <sunperf.h>

void dopmtr(char side, char uplo, char trans, int m, int n, double *ap, double *tau, double *c, int ldc, int *info);

void dopmtr_64(char side, char uplo, char trans, long m, long n, double *ap, double *tau, double *c, long ldc, long *info);

PURPOSE

dopmtr 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 of order nq, with nq = m if SIDE = 'L' and nq = n if SIDE = 'R'. Q is defined as the product of nq-1 elementary reflectors, as returned by SSPTRD using packed storage:

if UPLO = 'U', Q = H(nq-1) . . . H(2) H(1);

if UPLO = 'L', Q = H(1) H(2) . . . H(nq-1).

ARGUMENTS

• SIDE (input)
  

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

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

• UPLO (input)
  

   = 'U': Upper triangular packed storage used in previous
  call to SSPTRD;
   = 'L': Lower triangular packed storage used in previous
  call to SSPTRD.

• 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.

• AP (input)
  (M*(M+1)/2) if SIDE = 'L' (N*(N+1)/2) if SIDE = 'R' The vectors which define the elementary reflectors, as returned by SSPTRD. AP is modified by the routine but restored on exit.

• TAU (input)
  or (N-1) if SIDE = 'R' TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SSPTRD.

• 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)
  (N) if SIDE = 'L' (M) if SIDE = 'R'

• INFO (output)
  

   = 0:  successful exit

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