# ssymm.f

          SUBROUTINE SSYMM (SIDE, UPLO, M, N, ALPHA, A, LDA, B, LDB, BETA,
         $   C, LDC)
    C***BEGIN PROLOGUE  SSYMM
    C***PURPOSE  Multiply a real general matrix by a real symmetric matrix.
    C***LIBRARY   SLATEC (BLAS)
    C***CATEGORY  D1B6
    C***TYPE      SINGLE PRECISION (SSYMM-S, DSYMM-D, CSYMM-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  SSYMM  performs one of the matrix-matrix operations
    C
    C     C := alpha*A*B + beta*C,
    C
    C  or
    C
    C     C := alpha*B*A + beta*C,
    C
    C  where alpha and beta are scalars,  A is a symmetric matrix and  B and
    C  C are  m by n matrices.
    C
    C  Parameters
    C  ==========
    C
    C  SIDE   - CHARACTER*1.
    C           On entry,  SIDE  specifies whether  the  symmetric matrix  A
    C           appears on the  left or right  in the  operation as follows:
    C
    C              SIDE = 'L' or 'l'   C := alpha*A*B + beta*C,
    C
    C              SIDE = 'R' or 'r'   C := alpha*B*A + beta*C,
    C
    C           Unchanged on exit.
    C
    C  UPLO   - CHARACTER*1.
    C           On  entry,   UPLO  specifies  whether  the  upper  or  lower
    C           triangular  part  of  the  symmetric  matrix   A  is  to  be
    C           referenced as follows:
    C
    C              UPLO = 'U' or 'u'   Only the upper triangular part of the
    C                                  symmetric matrix is to be referenced.
    C
    C              UPLO = 'L' or 'l'   Only the lower triangular part of the
    C                                  symmetric matrix is to be referenced.
    C
    C           Unchanged on exit.
    C
    C  M      - INTEGER.
    C           On entry,  M  specifies the number of rows of the matrix  C.
    C           M  must be at least zero.
    C           Unchanged on exit.
    C
    C  N      - INTEGER.
    C           On entry, N specifies the number of columns of the matrix C.
    C           N  must be at least zero.
    C           Unchanged on exit.
    C
    C  ALPHA  - REAL            .
    C           On entry, ALPHA specifies the scalar alpha.
    C           Unchanged on exit.
    C
    C  A      - REAL             array of DIMENSION ( LDA, ka ), where ka is
    C           m  when  SIDE = 'L' or 'l'  and is  n otherwise.
    C           Before entry  with  SIDE = 'L' or 'l',  the  m by m  part of
    C           the array  A  must contain the  symmetric matrix,  such that
    C           when  UPLO = 'U' or 'u', the leading m by m upper triangular
    C           part of the array  A  must contain the upper triangular part
    C           of the  symmetric matrix and the  strictly  lower triangular
    C           part of  A  is not referenced,  and when  UPLO = 'L' or 'l',
    C           the leading  m by m  lower triangular part  of the  array  A
    C           must  contain  the  lower triangular part  of the  symmetric
    C           matrix and the  strictly upper triangular part of  A  is not
    C           referenced.
    C           Before entry  with  SIDE = 'R' or 'r',  the  n by n  part of
    C           the array  A  must contain the  symmetric matrix,  such that
    C           when  UPLO = 'U' or 'u', the leading n by n upper triangular
    C           part of the array  A  must contain the upper triangular part
    C           of the  symmetric matrix and the  strictly  lower triangular
    C           part of  A  is not referenced,  and when  UPLO = 'L' or 'l',
    C           the leading  n by n  lower triangular part  of the  array  A
    C           must  contain  the  lower triangular part  of the  symmetric
    C           matrix and the  strictly upper triangular part of  A  is not
    C           referenced.
    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 ), otherwise  LDA must be at
    C           least  max( 1, n ).
    C           Unchanged on exit.
    C
    C  B      - REAL             array of DIMENSION ( LDB, n ).
    C           Before entry, the leading  m by n part of the array  B  must
    C           contain the matrix B.
    C           Unchanged on exit.
    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  BETA   - REAL            .
    C           On entry,  BETA  specifies the scalar  beta.  When  BETA  is
    C           supplied as zero then C need not be set on input.
    C           Unchanged on exit.
    C
    C  C      - REAL             array of DIMENSION ( LDC, n ).
    C           Before entry, the leading  m by n  part of the array  C must
    C           contain the matrix  C,  except when  beta  is zero, in which
    C           case C need not be set on entry.
    C           On exit, the array  C  is overwritten by the  m by n updated
    C           matrix.
    C
    C  LDC    - INTEGER.
    C           On entry, LDC specifies the first dimension of C as declared
    C           in  the  calling  (sub)  program.   LDC  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  SSYMM