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      SUBROUTINE SSYMMF ( SIDE, UPLO, M, N, ALPHA, A, LDA, B, LDB,
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     $                   BETA, C, LDC )
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*     .. Scalar Arguments ..
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      CHARACTER*1        SIDE, UPLO
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      INTEGER            M, N, LDA, LDB, LDC
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      REAL               ALPHA, BETA
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*     .. Array Arguments ..
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      REAL               A( LDA, * ), B( LDB, * ), C( LDC, * )
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*     ..
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*
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*  Purpose
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*  =======
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*
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*  SSYMM  performs one of the matrix-matrix operations
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*
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*     C := alpha*A*B + beta*C,
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*
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*  or
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*
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*     C := alpha*B*A + beta*C,
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*
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*  where alpha and beta are scalars,  A is a symmetric matrix and  B and
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*  C are  m by n matrices.
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*
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*  Parameters
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*  ==========
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*
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*  SIDE   - CHARACTER*1.
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*           On entry,  SIDE  specifies whether  the  symmetric matrix  A
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*           appears on the  left or right  in the  operation as follows:
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*
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*              SIDE = 'L' or 'l'   C := alpha*A*B + beta*C,
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*
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*              SIDE = 'R' or 'r'   C := alpha*B*A + beta*C,
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*
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*           Unchanged on exit.
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*
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*  UPLO   - CHARACTER*1.
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*           On  entry,   UPLO  specifies  whether  the  upper  or  lower
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*           triangular  part  of  the  symmetric  matrix   A  is  to  be
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*           referenced as follows:
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*
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*              UPLO = 'U' or 'u'   Only the upper triangular part of the
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*                                  symmetric matrix is to be referenced.
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*
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*              UPLO = 'L' or 'l'   Only the lower triangular part of the
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*                                  symmetric matrix is to be referenced.
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*
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*           Unchanged on exit.
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*
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*  M      - INTEGER.
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*           On entry,  M  specifies the number of rows of the matrix  C.
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*           M  must be at least zero.
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*           Unchanged on exit.
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*
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*  N      - INTEGER.
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*           On entry, N specifies the number of columns of the matrix C.
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*           N  must be at least zero.
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*           Unchanged on exit.
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*
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*  ALPHA  - REAL            .
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*           On entry, ALPHA specifies the scalar alpha.
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*           Unchanged on exit.
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*
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*  A      - REAL             array of DIMENSION ( LDA, ka ), where ka is
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*           m  when  SIDE = 'L' or 'l'  and is  n otherwise.
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*           Before entry  with  SIDE = 'L' or 'l',  the  m by m  part of
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*           the array  A  must contain the  symmetric matrix,  such that
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*           when  UPLO = 'U' or 'u', the leading m by m upper triangular
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*           part of the array  A  must contain the upper triangular part
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*           of the  symmetric matrix and the  strictly  lower triangular
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*           part of  A  is not referenced,  and when  UPLO = 'L' or 'l',
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*           the leading  m by m  lower triangular part  of the  array  A
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*           must  contain  the  lower triangular part  of the  symmetric
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*           matrix and the  strictly upper triangular part of  A  is not
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*           referenced.
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*           Before entry  with  SIDE = 'R' or 'r',  the  n by n  part of
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*           the array  A  must contain the  symmetric matrix,  such that
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*           when  UPLO = 'U' or 'u', the leading n by n upper triangular
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*           part of the array  A  must contain the upper triangular part
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*           of the  symmetric matrix and the  strictly  lower triangular
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*           part of  A  is not referenced,  and when  UPLO = 'L' or 'l',
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*           the leading  n by n  lower triangular part  of the  array  A
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*           must  contain  the  lower triangular part  of the  symmetric
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*           matrix and the  strictly upper triangular part of  A  is not
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*           referenced.
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*           Unchanged on exit.
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*
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*  LDA    - INTEGER.
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*           On entry, LDA specifies the first dimension of A as declared
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*           in the calling (sub) program.  When  SIDE = 'L' or 'l'  then
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*           LDA must be at least  max( 1, m ), otherwise  LDA must be at
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*           least  max( 1, n ).
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*           Unchanged on exit.
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*
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*  B      - REAL             array of DIMENSION ( LDB, n ).
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*           Before entry, the leading  m by n part of the array  B  must
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*           contain the matrix B.
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*           Unchanged on exit.
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*
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*  LDB    - INTEGER.
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*           On entry, LDB specifies the first dimension of B as declared
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*           in  the  calling  (sub)  program.   LDB  must  be  at  least
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*           max( 1, m ).
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*           Unchanged on exit.
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*
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*  BETA   - REAL            .
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*           On entry,  BETA  specifies the scalar  beta.  When  BETA  is
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*           supplied as zero then C need not be set on input.
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*           Unchanged on exit.
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*
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*  C      - REAL             array of DIMENSION ( LDC, n ).
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*           Before entry, the leading  m by n  part of the array  C must
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*           contain the matrix  C,  except when  beta  is zero, in which
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*           case C need not be set on entry.
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*           On exit, the array  C  is overwritten by the  m by n updated
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*           matrix.
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*
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*  LDC    - INTEGER.
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*           On entry, LDC specifies the first dimension of C as declared
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*           in  the  calling  (sub)  program.   LDC  must  be  at  least
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*           max( 1, m ).
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*           Unchanged on exit.
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*
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*
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*  Level 3 Blas routine.
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*
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*  -- Written on 8-February-1989.
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*     Jack Dongarra, Argonne National Laboratory.
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*     Iain Duff, AERE Harwell.
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*     Jeremy Du Croz, Numerical Algorithms Group Ltd.
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*     Sven Hammarling, Numerical Algorithms Group Ltd.
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*
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*
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*     .. External Functions ..
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      LOGICAL            LSAME
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      EXTERNAL           LSAME
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*     .. External Subroutines ..
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      EXTERNAL           XERBLA
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*     .. Intrinsic Functions ..
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      INTRINSIC          MAX
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*     .. Local Scalars ..
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      LOGICAL            UPPER
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      INTEGER            I, INFO, J, K, NROWA
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      REAL               TEMP1, TEMP2
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*     .. Parameters ..
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      REAL               ONE         , ZERO
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      PARAMETER        ( ONE = 1.0E+0, ZERO = 0.0E+0 )
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*     ..
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*     .. Executable Statements ..
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*
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*     Set NROWA as the number of rows of A.
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*
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      IF( LSAME( SIDE, 'L' ) )THEN
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         NROWA = M
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      ELSE
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         NROWA = N
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      END IF
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      UPPER = LSAME( UPLO, 'U' )
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*
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*     Test the input parameters.
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*
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      INFO = 0
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      IF(      ( .NOT.LSAME( SIDE, 'L' ) ).AND.
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     $         ( .NOT.LSAME( SIDE, 'R' ) )      )THEN
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         INFO = 1
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      ELSE IF( ( .NOT.UPPER              ).AND.
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     $         ( .NOT.LSAME( UPLO, 'L' ) )      )THEN
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         INFO = 2
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      ELSE IF( M  .LT.0               )THEN
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         INFO = 3
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      ELSE IF( N  .LT.0               )THEN
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         INFO = 4
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      ELSE IF( LDA.LT.MAX( 1, NROWA ) )THEN
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         INFO = 7
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      ELSE IF( LDB.LT.MAX( 1, M     ) )THEN
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         INFO = 9
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      ELSE IF( LDC.LT.MAX( 1, M     ) )THEN
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         INFO = 12
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      END IF
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      IF( INFO.NE.0 )THEN
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         CALL XERBLA( 'SSYMM ', INFO )
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         RETURN
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      END IF
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*
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*     Quick return if possible.
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*
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      IF( ( M.EQ.0 ).OR.( N.EQ.0 ).OR.
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     $    ( ( ALPHA.EQ.ZERO ).AND.( BETA.EQ.ONE ) ) )
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     $   RETURN
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*
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*     And when  alpha.eq.zero.
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*
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      IF( ALPHA.EQ.ZERO )THEN
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         IF( BETA.EQ.ZERO )THEN
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            DO 20, J = 1, N
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               DO 10, I = 1, M
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                  C( I, J ) = ZERO
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   10          CONTINUE
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   20       CONTINUE
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         ELSE
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            DO 40, J = 1, N
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               DO 30, I = 1, M
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                  C( I, J ) = BETA*C( I, J )
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   30          CONTINUE
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   40       CONTINUE
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         END IF
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         RETURN
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      END IF
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*
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*     Start the operations.
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*
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      IF( LSAME( SIDE, 'L' ) )THEN
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*
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*        Form  C := alpha*A*B + beta*C.
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*
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         IF( UPPER )THEN
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            DO 70, J = 1, N
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               DO 60, I = 1, M
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                  TEMP1 = ALPHA*B( I, J )
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                  TEMP2 = ZERO
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                  DO 50, K = 1, I - 1
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                     C( K, J ) = C( K, J ) + TEMP1    *A( K, I )
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                     TEMP2     = TEMP2     + B( K, J )*A( K, I )
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   50             CONTINUE
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                  IF( BETA.EQ.ZERO )THEN
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                     C( I, J ) = TEMP1*A( I, I ) + ALPHA*TEMP2
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                  ELSE
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                     C( I, J ) = BETA *C( I, J ) +
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     $                           TEMP1*A( I, I ) + ALPHA*TEMP2
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                  END IF
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   60          CONTINUE
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   70       CONTINUE
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         ELSE
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            DO 100, J = 1, N
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               DO 90, I = M, 1, -1
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                  TEMP1 = ALPHA*B( I, J )
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                  TEMP2 = ZERO
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                  DO 80, K = I + 1, M
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                     C( K, J ) = C( K, J ) + TEMP1    *A( K, I )
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                     TEMP2     = TEMP2     + B( K, J )*A( K, I )
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   80             CONTINUE
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                  IF( BETA.EQ.ZERO )THEN
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                     C( I, J ) = TEMP1*A( I, I ) + ALPHA*TEMP2
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                  ELSE
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                     C( I, J ) = BETA *C( I, J ) +
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     $                           TEMP1*A( I, I ) + ALPHA*TEMP2
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                  END IF
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   90          CONTINUE
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  100       CONTINUE
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         END IF
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      ELSE
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*
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*        Form  C := alpha*B*A + beta*C.
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*
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         DO 170, J = 1, N
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            TEMP1 = ALPHA*A( J, J )
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            IF( BETA.EQ.ZERO )THEN
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               DO 110, I = 1, M
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                  C( I, J ) = TEMP1*B( I, J )
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  110          CONTINUE
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            ELSE
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               DO 120, I = 1, M
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                  C( I, J ) = BETA*C( I, J ) + TEMP1*B( I, J )
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  120          CONTINUE
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            END IF
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            DO 140, K = 1, J - 1
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               IF( UPPER )THEN
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                  TEMP1 = ALPHA*A( K, J )
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               ELSE
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                  TEMP1 = ALPHA*A( J, K )
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               END IF
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               DO 130, I = 1, M
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                  C( I, J ) = C( I, J ) + TEMP1*B( I, K )
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  130          CONTINUE
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  140       CONTINUE
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            DO 160, K = J + 1, N
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               IF( UPPER )THEN
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                  TEMP1 = ALPHA*A( J, K )
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               ELSE
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                  TEMP1 = ALPHA*A( K, J )
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               END IF
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               DO 150, I = 1, M
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                  C( I, J ) = C( I, J ) + TEMP1*B( I, K )
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  150          CONTINUE
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  160       CONTINUE
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  170    CONTINUE
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      END IF
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*
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      RETURN
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*
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*     End of SSYMM .
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*
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      END