Contents

• 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.

               TRANS is defaulted to 'N' for F95 INTERFACE.

     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 ille-
               gal value