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      SUBROUTINE ZGEMM(TRANSA,TRANSB,M,N,K,ALPHA,A,LDA,B,LDB,BETA,C,LDC)
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*     .. Scalar Arguments ..
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      DOUBLE COMPLEX ALPHA,BETA
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      INTEGER K,LDA,LDB,LDC,M,N
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      CHARACTER TRANSA,TRANSB
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*     ..
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*     .. Array Arguments ..
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      DOUBLE COMPLEX 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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*  ZGEMM  performs one of the matrix-matrix operations
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*
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*     C := alpha*op( A )*op( B ) + beta*C,
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*
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*  where  op( X ) is one of
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*
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*     op( X ) = X   or   op( X ) = X'   or   op( X ) = conjg( X' ),
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*
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*  alpha and beta are scalars, and A, B and C are matrices, with op( A )
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*  an m by k matrix,  op( B )  a  k by n matrix and  C an m by n matrix.
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*
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*  Arguments
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*  ==========
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*
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*  TRANSA - CHARACTER*1.
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*           On entry, TRANSA specifies the form of op( A ) to be used in
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*           the matrix multiplication as follows:
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*
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*              TRANSA = 'N' or 'n',  op( A ) = A.
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*
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*              TRANSA = 'T' or 't',  op( A ) = A'.
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*
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*              TRANSA = 'C' or 'c',  op( A ) = conjg( A' ).
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*
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*           Unchanged on exit.
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*
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*  TRANSB - CHARACTER*1.
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*           On entry, TRANSB specifies the form of op( B ) to be used in
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*           the matrix multiplication as follows:
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*
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*              TRANSB = 'N' or 'n',  op( B ) = B.
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*
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*              TRANSB = 'T' or 't',  op( B ) = B'.
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*
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*              TRANSB = 'C' or 'c',  op( B ) = conjg( B' ).
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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
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*           op( A )  and of the  matrix  C.  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
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*           op( B ) and the number of columns of the matrix C. N must be
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*           at least zero.
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*           Unchanged on exit.
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*
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*  K      - INTEGER.
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*           On entry,  K  specifies  the number of columns of the matrix
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*           op( A ) and the number of rows of the matrix op( B ). K must
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*           be at least  zero.
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*           Unchanged on exit.
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*
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*  ALPHA  - COMPLEX*16      .
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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      - COMPLEX*16       array of DIMENSION ( LDA, ka ), where ka is
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*           k  when  TRANSA = 'N' or 'n',  and is  m  otherwise.
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*           Before entry with  TRANSA = 'N' or 'n',  the leading  m by k
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*           part of the array  A  must contain the matrix  A,  otherwise
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*           the leading  k by m  part of the array  A  must contain  the
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*           matrix A.
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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  TRANSA = 'N' or 'n' 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, k ).
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*           Unchanged on exit.
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*
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*  B      - COMPLEX*16       array of DIMENSION ( LDB, kb ), where kb is
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*           n  when  TRANSB = 'N' or 'n',  and is  k  otherwise.
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*           Before entry with  TRANSB = 'N' or 'n',  the leading  k by n
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*           part of the array  B  must contain the matrix  B,  otherwise
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*           the leading  n by k  part of the array  B  must contain  the
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*           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. When  TRANSB = 'N' or 'n' then
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*           LDB must be at least  max( 1, k ), otherwise  LDB 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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*  BETA   - COMPLEX*16      .
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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      - COMPLEX*16       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  matrix
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*           ( alpha*op( A )*op( B ) + beta*C ).
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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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*     ..
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*     .. External Subroutines ..
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      EXTERNAL XERBLA
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*     ..
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*     .. Intrinsic Functions ..
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      INTRINSIC DCONJG,MAX
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*     ..
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*     .. Local Scalars ..
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      DOUBLE COMPLEX TEMP
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      INTEGER I,INFO,J,L,NCOLA,NROWA,NROWB
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      LOGICAL CONJA,CONJB,NOTA,NOTB
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*     ..
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*     .. Parameters ..
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      DOUBLE COMPLEX ONE
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      PARAMETER (ONE= (1.0D+0,0.0D+0))
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      DOUBLE COMPLEX ZERO
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      PARAMETER (ZERO= (0.0D+0,0.0D+0))
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*     ..
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*
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*     Set  NOTA  and  NOTB  as  true if  A  and  B  respectively are not
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*     conjugated or transposed, set  CONJA and CONJB  as true if  A  and
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*     B  respectively are to be  transposed but  not conjugated  and set
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*     NROWA, NCOLA and  NROWB  as the number of rows and  columns  of  A
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*     and the number of rows of  B  respectively.
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*
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      NOTA = LSAME(TRANSA,'N')
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      NOTB = LSAME(TRANSB,'N')
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      CONJA = LSAME(TRANSA,'C')
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      CONJB = LSAME(TRANSB,'C')
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      IF (NOTA) THEN
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          NROWA = M
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          NCOLA = K
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      ELSE
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          NROWA = K
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          NCOLA = M
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      END IF
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      IF (NOTB) THEN
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          NROWB = K
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      ELSE
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          NROWB = N
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      END IF
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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.NOTA) .AND. (.NOT.CONJA) .AND.
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     +    (.NOT.LSAME(TRANSA,'T'))) THEN
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          INFO = 1
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      ELSE IF ((.NOT.NOTB) .AND. (.NOT.CONJB) .AND.
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     +         (.NOT.LSAME(TRANSB,'T'))) 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 (K.LT.0) THEN
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          INFO = 5
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      ELSE IF (LDA.LT.MAX(1,NROWA)) THEN
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          INFO = 8
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      ELSE IF (LDB.LT.MAX(1,NROWB)) THEN
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          INFO = 10
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      ELSE IF (LDC.LT.MAX(1,M)) THEN
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          INFO = 13
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      END IF
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      IF (INFO.NE.0) THEN
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          CALL XERBLA('ZGEMM ',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).OR. (K.EQ.0)).AND. (BETA.EQ.ONE))) 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 (NOTB) THEN
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          IF (NOTA) THEN
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*
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*           Form  C := alpha*A*B + beta*C.
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*
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              DO 90 J = 1,N
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                  IF (BETA.EQ.ZERO) THEN
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                      DO 50 I = 1,M
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                          C(I,J) = ZERO
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   50                 CONTINUE
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                  ELSE IF (BETA.NE.ONE) THEN
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                      DO 60 I = 1,M
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                          C(I,J) = BETA*C(I,J)
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   60                 CONTINUE
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                  END IF
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                  DO 80 L = 1,K
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                      IF (B(L,J).NE.ZERO) THEN
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                          TEMP = ALPHA*B(L,J)
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                          DO 70 I = 1,M
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                              C(I,J) = C(I,J) + TEMP*A(I,L)
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   70                     CONTINUE
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                      END IF
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   80             CONTINUE
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   90         CONTINUE
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          ELSE IF (CONJA) THEN
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*
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*           Form  C := alpha*conjg( A' )*B + beta*C.
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*
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              DO 120 J = 1,N
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                  DO 110 I = 1,M
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                      TEMP = ZERO
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                      DO 100 L = 1,K
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                          TEMP = TEMP + DCONJG(A(L,I))*B(L,J)
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  100                 CONTINUE
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                      IF (BETA.EQ.ZERO) THEN
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                          C(I,J) = ALPHA*TEMP
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                      ELSE
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                          C(I,J) = ALPHA*TEMP + BETA*C(I,J)
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                      END IF
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  110             CONTINUE
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  120         CONTINUE
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          ELSE
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*
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*           Form  C := alpha*A'*B + beta*C
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*
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              DO 150 J = 1,N
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                  DO 140 I = 1,M
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                      TEMP = ZERO
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                      DO 130 L = 1,K
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                          TEMP = TEMP + A(L,I)*B(L,J)
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  130                 CONTINUE
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                      IF (BETA.EQ.ZERO) THEN
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                          C(I,J) = ALPHA*TEMP
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                      ELSE
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                          C(I,J) = ALPHA*TEMP + BETA*C(I,J)
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                      END IF
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  140             CONTINUE
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  150         CONTINUE
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          END IF
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      ELSE IF (NOTA) THEN
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          IF (CONJB) THEN
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*
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*           Form  C := alpha*A*conjg( B' ) + beta*C.
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*
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              DO 200 J = 1,N
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                  IF (BETA.EQ.ZERO) THEN
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                      DO 160 I = 1,M
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                          C(I,J) = ZERO
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  160                 CONTINUE
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                  ELSE IF (BETA.NE.ONE) THEN
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                      DO 170 I = 1,M
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                          C(I,J) = BETA*C(I,J)
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  170                 CONTINUE
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                  END IF
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                  DO 190 L = 1,K
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                      IF (B(J,L).NE.ZERO) THEN
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                          TEMP = ALPHA*DCONJG(B(J,L))
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                          DO 180 I = 1,M
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                              C(I,J) = C(I,J) + TEMP*A(I,L)
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  180                     CONTINUE
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                      END IF
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  190             CONTINUE
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  200         CONTINUE
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          ELSE
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*
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*           Form  C := alpha*A*B'          + beta*C
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*
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              DO 250 J = 1,N
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                  IF (BETA.EQ.ZERO) THEN
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                      DO 210 I = 1,M
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                          C(I,J) = ZERO
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  210                 CONTINUE
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                  ELSE IF (BETA.NE.ONE) THEN
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                      DO 220 I = 1,M
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                          C(I,J) = BETA*C(I,J)
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  220                 CONTINUE
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                  END IF
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                  DO 240 L = 1,K
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                      IF (B(J,L).NE.ZERO) THEN
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                          TEMP = ALPHA*B(J,L)
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                          DO 230 I = 1,M
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                              C(I,J) = C(I,J) + TEMP*A(I,L)
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  230                     CONTINUE
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                      END IF
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  240             CONTINUE
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  250         CONTINUE
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          END IF
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      ELSE IF (CONJA) THEN
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          IF (CONJB) THEN
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*
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*           Form  C := alpha*conjg( A' )*conjg( B' ) + beta*C.
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*
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              DO 280 J = 1,N
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                  DO 270 I = 1,M
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                      TEMP = ZERO
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                      DO 260 L = 1,K
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                          TEMP = TEMP + DCONJG(A(L,I))*DCONJG(B(J,L))
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  260                 CONTINUE
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                      IF (BETA.EQ.ZERO) THEN
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                          C(I,J) = ALPHA*TEMP
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                      ELSE
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                          C(I,J) = ALPHA*TEMP + BETA*C(I,J)
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                      END IF
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  270             CONTINUE
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  280         CONTINUE
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          ELSE
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*
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*           Form  C := alpha*conjg( A' )*B' + beta*C
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*
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              DO 310 J = 1,N
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                  DO 300 I = 1,M
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                      TEMP = ZERO
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                      DO 290 L = 1,K
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                          TEMP = TEMP + DCONJG(A(L,I))*B(J,L)
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  290                 CONTINUE
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                      IF (BETA.EQ.ZERO) THEN
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                          C(I,J) = ALPHA*TEMP
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                      ELSE
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                          C(I,J) = ALPHA*TEMP + BETA*C(I,J)
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                      END IF
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  300             CONTINUE
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  310         CONTINUE
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          END IF
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      ELSE
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          IF (CONJB) THEN
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*
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*           Form  C := alpha*A'*conjg( B' ) + beta*C
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*
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              DO 340 J = 1,N
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                  DO 330 I = 1,M
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                      TEMP = ZERO
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                      DO 320 L = 1,K
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                          TEMP = TEMP + A(L,I)*DCONJG(B(J,L))
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  320                 CONTINUE
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                      IF (BETA.EQ.ZERO) THEN
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                          C(I,J) = ALPHA*TEMP
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                      ELSE
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                          C(I,J) = ALPHA*TEMP + BETA*C(I,J)
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                      END IF
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  330             CONTINUE
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  340         CONTINUE
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          ELSE
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*
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*           Form  C := alpha*A'*B' + beta*C
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*
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              DO 370 J = 1,N
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                  DO 360 I = 1,M
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                      TEMP = ZERO
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                      DO 350 L = 1,K
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                          TEMP = TEMP + A(L,I)*B(J,L)
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  350                 CONTINUE
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                      IF (BETA.EQ.ZERO) THEN
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                          C(I,J) = ALPHA*TEMP
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                      ELSE
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                          C(I,J) = ALPHA*TEMP + BETA*C(I,J)
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                      END IF
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  360             CONTINUE
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  370         CONTINUE
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          END IF
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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 ZGEMM .
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*
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      END