```      SUBROUTINE ZHEMM(SIDE,UPLO,M,N,ALPHA,A,LDA,B,LDB,BETA,C,LDC)
*     .. Scalar Arguments ..
DOUBLE COMPLEX ALPHA,BETA
INTEGER LDA,LDB,LDC,M,N
CHARACTER SIDE,UPLO
*     ..
*     .. Array Arguments ..
DOUBLE COMPLEX A(LDA,*),B(LDB,*),C(LDC,*)
*     ..
*
*  Purpose
*  =======
*
*  ZHEMM  performs one of the matrix-matrix operations
*
*     C := alpha*A*B + beta*C,
*
*  or
*
*     C := alpha*B*A + beta*C,
*
*  where alpha and beta are scalars, A is an hermitian matrix and  B and
*  C are m by n matrices.
*
*  Arguments
*  ==========
*
*  SIDE   - CHARACTER*1.
*           On entry,  SIDE  specifies whether  the  hermitian matrix  A
*           appears on the  left or right  in the  operation as follows:
*
*              SIDE = 'L' or 'l'   C := alpha*A*B + beta*C,
*
*              SIDE = 'R' or 'r'   C := alpha*B*A + beta*C,
*
*           Unchanged on exit.
*
*  UPLO   - CHARACTER*1.
*           On  entry,   UPLO  specifies  whether  the  upper  or  lower
*           triangular  part  of  the  hermitian  matrix   A  is  to  be
*           referenced as follows:
*
*              UPLO = 'U' or 'u'   Only the upper triangular part of the
*                                  hermitian matrix is to be referenced.
*
*              UPLO = 'L' or 'l'   Only the lower triangular part of the
*                                  hermitian matrix is to be referenced.
*
*           Unchanged on exit.
*
*  M      - INTEGER.
*           On entry,  M  specifies the number of rows of the matrix  C.
*           M  must be at least zero.
*           Unchanged on exit.
*
*  N      - INTEGER.
*           On entry, N specifies the number of columns of the matrix C.
*           N  must be at least zero.
*           Unchanged on exit.
*
*  ALPHA  - COMPLEX*16      .
*           On entry, ALPHA specifies the scalar alpha.
*           Unchanged on exit.
*
*  A      - COMPLEX*16       array of DIMENSION ( LDA, ka ), where ka is
*           m  when  SIDE = 'L' or 'l'  and is n  otherwise.
*           Before entry  with  SIDE = 'L' or 'l',  the  m by m  part of
*           the array  A  must contain the  hermitian matrix,  such that
*           when  UPLO = 'U' or 'u', the leading m by m upper triangular
*           part of the array  A  must contain the upper triangular part
*           of the  hermitian matrix and the  strictly  lower triangular
*           part of  A  is not referenced,  and when  UPLO = 'L' or 'l',
*           the leading  m by m  lower triangular part  of the  array  A
*           must  contain  the  lower triangular part  of the  hermitian
*           matrix and the  strictly upper triangular part of  A  is not
*           referenced.
*           Before entry  with  SIDE = 'R' or 'r',  the  n by n  part of
*           the array  A  must contain the  hermitian matrix,  such that
*           when  UPLO = 'U' or 'u', the leading n by n upper triangular
*           part of the array  A  must contain the upper triangular part
*           of the  hermitian matrix and the  strictly  lower triangular
*           part of  A  is not referenced,  and when  UPLO = 'L' or 'l',
*           the leading  n by n  lower triangular part  of the  array  A
*           must  contain  the  lower triangular part  of the  hermitian
*           matrix and the  strictly upper triangular part of  A  is not
*           referenced.
*           Note that the imaginary parts  of the diagonal elements need
*           not be set, they are assumed to be zero.
*           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 ), otherwise  LDA must be at
*           least max( 1, n ).
*           Unchanged on exit.
*
*  B      - COMPLEX*16       array of DIMENSION ( LDB, n ).
*           Before entry, the leading  m by n part of the array  B  must
*           contain the matrix B.
*           Unchanged on exit.
*
*  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.
*
*  BETA   - COMPLEX*16      .
*           On entry,  BETA  specifies the scalar  beta.  When  BETA  is
*           supplied as zero then C need not be set on input.
*           Unchanged on exit.
*
*  C      - COMPLEX*16       array of DIMENSION ( LDC, n ).
*           Before entry, the leading  m by n  part of the array  C must
*           contain the matrix  C,  except when  beta  is zero, in which
*           case C need not be set on entry.
*           On exit, the array  C  is overwritten by the  m by n updated
*           matrix.
*
*  LDC    - INTEGER.
*           On entry, LDC specifies the first dimension of C as declared
*           in  the  calling  (sub)  program.   LDC  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.
*
*
*     .. External Functions ..
LOGICAL LSAME
EXTERNAL LSAME
*     ..
*     .. External Subroutines ..
EXTERNAL XERBLA
*     ..
*     .. Intrinsic Functions ..
INTRINSIC DBLE,DCONJG,MAX
*     ..
*     .. Local Scalars ..
DOUBLE COMPLEX TEMP1,TEMP2
INTEGER I,INFO,J,K,NROWA
LOGICAL UPPER
*     ..
*     .. Parameters ..
DOUBLE COMPLEX ONE
PARAMETER (ONE= (1.0D+0,0.0D+0))
DOUBLE COMPLEX ZERO
PARAMETER (ZERO= (0.0D+0,0.0D+0))
*     ..
*
*     Set NROWA as the number of rows of A.
*
IF (LSAME(SIDE,'L')) THEN
NROWA = M
ELSE
NROWA = N
END IF
UPPER = LSAME(UPLO,'U')
*
*     Test the input parameters.
*
INFO = 0
IF ((.NOT.LSAME(SIDE,'L')) .AND. (.NOT.LSAME(SIDE,'R'))) THEN
INFO = 1
ELSE IF ((.NOT.UPPER) .AND. (.NOT.LSAME(UPLO,'L'))) THEN
INFO = 2
ELSE IF (M.LT.0) THEN
INFO = 3
ELSE IF (N.LT.0) THEN
INFO = 4
ELSE IF (LDA.LT.MAX(1,NROWA)) THEN
INFO = 7
ELSE IF (LDB.LT.MAX(1,M)) THEN
INFO = 9
ELSE IF (LDC.LT.MAX(1,M)) THEN
INFO = 12
END IF
IF (INFO.NE.0) THEN
CALL XERBLA('ZHEMM ',INFO)
RETURN
END IF
*
*     Quick return if possible.
*
IF ((M.EQ.0) .OR. (N.EQ.0) .OR.
+    ((ALPHA.EQ.ZERO).AND. (BETA.EQ.ONE))) RETURN
*
*     And when  alpha.eq.zero.
*
IF (ALPHA.EQ.ZERO) THEN
IF (BETA.EQ.ZERO) THEN
DO 20 J = 1,N
DO 10 I = 1,M
C(I,J) = ZERO
10             CONTINUE
20         CONTINUE
ELSE
DO 40 J = 1,N
DO 30 I = 1,M
C(I,J) = BETA*C(I,J)
30             CONTINUE
40         CONTINUE
END IF
RETURN
END IF
*
*     Start the operations.
*
IF (LSAME(SIDE,'L')) THEN
*
*        Form  C := alpha*A*B + beta*C.
*
IF (UPPER) THEN
DO 70 J = 1,N
DO 60 I = 1,M
TEMP1 = ALPHA*B(I,J)
TEMP2 = ZERO
DO 50 K = 1,I - 1
C(K,J) = C(K,J) + TEMP1*A(K,I)
TEMP2 = TEMP2 + B(K,J)*DCONJG(A(K,I))
50                 CONTINUE
IF (BETA.EQ.ZERO) THEN
C(I,J) = TEMP1*DBLE(A(I,I)) + ALPHA*TEMP2
ELSE
C(I,J) = BETA*C(I,J) + TEMP1*DBLE(A(I,I)) +
+                             ALPHA*TEMP2
END IF
60             CONTINUE
70         CONTINUE
ELSE
DO 100 J = 1,N
DO 90 I = M,1,-1
TEMP1 = ALPHA*B(I,J)
TEMP2 = ZERO
DO 80 K = I + 1,M
C(K,J) = C(K,J) + TEMP1*A(K,I)
TEMP2 = TEMP2 + B(K,J)*DCONJG(A(K,I))
80                 CONTINUE
IF (BETA.EQ.ZERO) THEN
C(I,J) = TEMP1*DBLE(A(I,I)) + ALPHA*TEMP2
ELSE
C(I,J) = BETA*C(I,J) + TEMP1*DBLE(A(I,I)) +
+                             ALPHA*TEMP2
END IF
90             CONTINUE
100         CONTINUE
END IF
ELSE
*
*        Form  C := alpha*B*A + beta*C.
*
DO 170 J = 1,N
TEMP1 = ALPHA*DBLE(A(J,J))
IF (BETA.EQ.ZERO) THEN
DO 110 I = 1,M
C(I,J) = TEMP1*B(I,J)
110             CONTINUE
ELSE
DO 120 I = 1,M
C(I,J) = BETA*C(I,J) + TEMP1*B(I,J)
120             CONTINUE
END IF
DO 140 K = 1,J - 1
IF (UPPER) THEN
TEMP1 = ALPHA*A(K,J)
ELSE
TEMP1 = ALPHA*DCONJG(A(J,K))
END IF
DO 130 I = 1,M
C(I,J) = C(I,J) + TEMP1*B(I,K)
130             CONTINUE
140         CONTINUE
DO 160 K = J + 1,N
IF (UPPER) THEN
TEMP1 = ALPHA*DCONJG(A(J,K))
ELSE
TEMP1 = ALPHA*A(K,J)
END IF
DO 150 I = 1,M
C(I,J) = C(I,J) + TEMP1*B(I,K)
150             CONTINUE
160         CONTINUE
170     CONTINUE
END IF
*
RETURN
*
*     End of ZHEMM .
*
END

```