dtrmm.f

SUBROUTINE DTRMM (SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA,
\$   B, LDB)
C***BEGIN PROLOGUE  DTRMM
C***PURPOSE  Perform one of the matrix-matrix operations.
C***LIBRARY   SLATEC (BLAS)
C***CATEGORY  D1B6
C***TYPE      DOUBLE PRECISION (STRMM-S, DTRMM-D, CTRMM-C)
C***KEYWORDS  LEVEL 3 BLAS, LINEAR ALGEBRA
C***AUTHOR  Dongarra, J., (ANL)
C           Duff, I., (AERE)
C           Du Croz, J., (NAG)
C           Hammarling, S. (NAG)
C***DESCRIPTION
C
C  DTRMM  performs one of the matrix-matrix operations
C
C     B := alpha*op( A )*B,   or   B := alpha*B*op( A ),
C
C  where  alpha  is a scalar,  B  is an m by n matrix,  A  is a unit, or
C  non-unit,  upper or lower triangular matrix  and  op( A )  is one  of
C
C     op( A ) = A   or   op( A ) = A'.
C
C  Parameters
C  ==========
C
C  SIDE   - CHARACTER*1.
C           On entry,  SIDE specifies whether  op( A ) multiplies B from
C           the left or right as follows:
C
C              SIDE = 'L' or 'l'   B := alpha*op( A )*B.
C
C              SIDE = 'R' or 'r'   B := alpha*B*op( A ).
C
C           Unchanged on exit.
C
C  UPLO   - CHARACTER*1.
C           On entry, UPLO specifies whether the matrix A is an upper or
C           lower triangular matrix as follows:
C
C              UPLO = 'U' or 'u'   A is an upper triangular matrix.
C
C              UPLO = 'L' or 'l'   A is a lower triangular matrix.
C
C           Unchanged on exit.
C
C  TRANSA - CHARACTER*1.
C           On entry, TRANSA specifies the form of op( A ) to be used in
C           the matrix multiplication as follows:
C
C              TRANSA = 'N' or 'n'   op( A ) = A.
C
C              TRANSA = 'T' or 't'   op( A ) = A'.
C
C              TRANSA = 'C' or 'c'   op( A ) = A'.
C
C           Unchanged on exit.
C
C  DIAG   - CHARACTER*1.
C           On entry, DIAG specifies whether or not A is unit triangular
C           as follows:
C
C              DIAG = 'U' or 'u'   A is assumed to be unit triangular.
C
C              DIAG = 'N' or 'n'   A is not assumed to be unit
C                                  triangular.
C
C           Unchanged on exit.
C
C  M      - INTEGER.
C           On entry, M specifies the number of rows of B. M must be at
C           least zero.
C           Unchanged on exit.
C
C  N      - INTEGER.
C           On entry, N specifies the number of columns of B.  N must be
C           at least zero.
C           Unchanged on exit.
C
C  ALPHA  - DOUBLE PRECISION.
C           On entry,  ALPHA specifies the scalar  alpha. When  alpha is
C           zero then  A is not referenced and  B need not be set before
C           entry.
C           Unchanged on exit.
C
C  A      - DOUBLE PRECISION array of DIMENSION ( LDA, k ), where k is m
C           when  SIDE = 'L' or 'l'  and is  n  when  SIDE = 'R' or 'r'.
C           Before entry  with  UPLO = 'U' or 'u',  the  leading  k by k
C           upper triangular part of the array  A must contain the upper
C           triangular matrix  and the strictly lower triangular part of
C           A is not referenced.
C           Before entry  with  UPLO = 'L' or 'l',  the  leading  k by k
C           lower triangular part of the array  A must contain the lower
C           triangular matrix  and the strictly upper triangular part of
C           A is not referenced.
C           Note that when  DIAG = 'U' or 'u',  the diagonal elements of
C           A  are not referenced either,  but are assumed to be  unity.
C           Unchanged on exit.
C
C  LDA    - INTEGER.
C           On entry, LDA specifies the first dimension of A as declared
C           in the calling (sub) program.  When  SIDE = 'L' or 'l'  then
C           LDA  must be at least  max( 1, m ),  when  SIDE = 'R' or 'r'
C           then LDA must be at least max( 1, n ).
C           Unchanged on exit.
C
C  B      - DOUBLE PRECISION array of DIMENSION ( LDB, n ).
C           Before entry,  the leading  m by n part of the array  B must
C           contain the matrix  B,  and  on exit  is overwritten  by the
C           transformed matrix.
C
C  LDB    - INTEGER.
C           On entry, LDB specifies the first dimension of B as declared
C           in  the  calling  (sub)  program.   LDB  must  be  at  least
C           max( 1, m ).
C           Unchanged on exit.
C
C***REFERENCES  Dongarra, J., Du Croz, J., Duff, I., and Hammarling, S.
C                 A set of level 3 basic linear algebra subprograms.
C                 ACM TOMS, Vol. 16, No. 1, pp. 1-17, March 1990.
C***ROUTINES CALLED  LSAME, XERBLA
C***REVISION HISTORY  (YYMMDD)
C   890208  DATE WRITTEN
C   910605  Modified to meet SLATEC prologue standards.  Only comment
C           lines were modified.  (BKS)
C***END PROLOGUE  DTRMM