NAME

       DTRMM  -  perform  one  of  the  matrix-matrix  operations   B := alpha*op( A )*B, or B :=
       alpha*B*op( A ),

SYNOPSIS

       SUBROUTINE DTRMM ( SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA, B, LDB )

           CHARACTER*1  SIDE, UPLO, TRANSA, DIAG

           INTEGER      M, N, LDA, LDB

           DOUBLE       PRECISION ALPHA

           DOUBLE       PRECISION A( LDA, * ), B( LDB, * )

PURPOSE

       DTRMM  performs one of the matrix-matrix operations

       where  alpha  is a scalar,  B  is an m by n matrix,  A  is a unit, or non-unit,  upper  or
       lower triangular matrix  and  op( A )  is one  of

          op( A ) = A   or   op( A ) = A'.

PARAMETERS

       SIDE   - CHARACTER*1.
              On  entry,   SIDE specifies whether  op( A ) multiplies B from the left or right as
              follows:

              SIDE = 'L' or 'l'   B := alpha*op( A )*B.

              SIDE = 'R' or 'r'   B := alpha*B*op( A ).

              Unchanged on exit.

       UPLO   - CHARACTER*1.
              On entry, UPLO specifies whether the matrix A  is  an  upper  or  lower  triangular
              matrix as follows:

              UPLO = 'U' or 'u'   A is an upper triangular matrix.

              UPLO = 'L' or 'l'   A is a lower triangular matrix.

              Unchanged on exit.

              TRANSA - CHARACTER*1.  On entry, TRANSA specifies the form of op( A ) to be used in
              the matrix multiplication as follows:

              TRANSA = 'N' or 'n'   op( A ) = A.

              TRANSA = 'T' or 't'   op( A ) = A'.

              TRANSA = 'C' or 'c'   op( A ) = A'.

              Unchanged on exit.

       DIAG   - CHARACTER*1.
              On entry, DIAG specifies whether or not A is unit triangular as follows:

              DIAG = 'U' or 'u'   A is assumed to be unit triangular.

              DIAG = 'N' or 'n'   A is not assumed to be unit triangular.

              Unchanged on exit.

       M      - INTEGER.
              On entry, M specifies the number of rows of B. M must be at least zero.   Unchanged
              on exit.

       N      - INTEGER.
              On  entry,  N  specifies  the  number  of  columns  of B.  N must be at least zero.
              Unchanged on exit.

       ALPHA  - DOUBLE PRECISION.
              On entry,  ALPHA specifies the scalar  alpha. When  alpha is zero then   A  is  not
              referenced and  B need not be set before entry.  Unchanged on exit.

       A      - DOUBLE PRECISION array of DIMENSION ( LDA, k ), where k is m
              when   SIDE  =  'L' or 'l'  and is  n  when  SIDE = 'R' or 'r'.  Before entry  with
              UPLO = 'U' or 'u',  the  leading  k by k upper triangular part of the array  A must
              contain the upper triangular matrix  and the strictly lower triangular part of A is
              not referenced.  Before entry  with  UPLO = 'L' or 'l',  the  leading  k by k lower
              triangular  part  of the array  A must contain the lower triangular matrix  and the
              strictly upper triangular part of A is not referenced.  Note that when  DIAG =  'U'
              or 'u',  the diagonal elements of A  are not referenced either,  but are assumed to
              be  unity.  Unchanged on exit.

       LDA    - INTEGER.
              On entry, LDA specifies the first dimension of A as declared in the  calling  (sub)
              program.   When   SIDE = 'L' or 'l'  then LDA  must be at least  max( 1, m ),  when
              SIDE = 'R' or 'r' then LDA must be at least max( 1, n ).  Unchanged on exit.

       B      - DOUBLE PRECISION array of DIMENSION ( LDB, n ).
              Before entry,  the leading  m by n part of the array  B must contain the matrix  B,
              and  on exit  is overwritten  by the transformed matrix.

       LDB    - INTEGER.
              On  entry,  LDB  specifies  the  first  dimension of B as declared in  the  calling
              (sub)  program.   LDB  must  be  at  least max( 1, m ).  Unchanged on exit.

              Level 3 Blas routine.

              -- Written on 8-February-1989.  Jack Dongarra, Argonne National  Laboratory.   Iain
              Duff,  AERE  Harwell.   Jeremy  Du  Croz,  Numerical  Algorithms  Group  Ltd.  Sven
              Hammarling, Numerical Algorithms Group Ltd.