!>
!> ZGEMMTR  performs one of the matrix-matrix operations
!>
!>    C := alpha*op( A )*op( B ) + beta*C,
!>
!> where  op( X ) is one of
!>
!>    op( X ) = X   or   op( X ) = X**T,
!>
!> alpha and beta are scalars, and A, B and C are matrices, with op( A )
!> an n by k matrix,  op( B )  a  k by n matrix and  C an n by n matrix.
!> Thereby, the routine only accesses and updates the upper or lower
!> triangular part of the result matrix C. This behaviour can be used if
!> the resulting matrix C is known to be Hermitian or symmetric.
!> 

UPLO

!>          UPLO is CHARACTER*1
!>           On entry, UPLO specifies whether the lower or the upper
!>           triangular part of C is access and updated.
!>
!>              UPLO = 'L' or 'l', the lower triangular part of C is used.
!>
!>              UPLO = 'U' or 'u', the upper triangular part of C is used.
!> 

TRANSA

!>          TRANSA is 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**T.
!>
!>              TRANSA = 'C' or 'c',  op( A ) = A**H.
!> 

TRANSB

!>          TRANSB is CHARACTER*1
!>           On entry, TRANSB specifies the form of op( B ) to be used in
!>           the matrix multiplication as follows:
!>
!>              TRANSB = 'N' or 'n',  op( B ) = B.
!>
!>              TRANSB = 'T' or 't',  op( B ) = B**T.
!>
!>              TRANSB = 'C' or 'c',  op( B ) = B**H.
!> 

N

!>          N is INTEGER
!>           On entry,  N specifies the number of rows and columns of
!>           the matrix C, the number of columns of op(B) and the number
!>           of rows of op(A).  N must be at least zero.
!> 

K

!>          K is INTEGER
!>           On entry,  K  specifies  the number of columns of the matrix
!>           op( A ) and the number of rows of the matrix op( B ). K must
!>           be at least  zero.
!> 

ALPHA

!>          ALPHA is COMPLEX*16.
!>           On entry, ALPHA specifies the scalar alpha.
!> 

A

!>          A is COMPLEX*16 array, dimension ( LDA, ka ), where ka is
!>           k  when  TRANSA = 'N' or 'n',  and is  n  otherwise.
!>           Before entry with  TRANSA = 'N' or 'n',  the leading  n by k
!>           part of the array  A  must contain the matrix  A,  otherwise
!>           the leading  k by m  part of the array  A  must contain  the
!>           matrix A.
!> 

LDA

!>          LDA is INTEGER
!>           On entry, LDA specifies the first dimension of A as declared
!>           in the calling (sub) program. When  TRANSA = 'N' or 'n' then
!>           LDA must be at least  max( 1, n ), otherwise  LDA must be at
!>           least  max( 1, k ).
!> 

B

!>          B is COMPLEX*16 array, dimension ( LDB, kb ), where kb is
!>           n  when  TRANSB = 'N' or 'n',  and is  k  otherwise.
!>           Before entry with  TRANSB = 'N' or 'n',  the leading  k by n
!>           part of the array  B  must contain the matrix  B,  otherwise
!>           the leading  n by k  part of the array  B  must contain  the
!>           matrix B.
!> 

LDB

!>          LDB is INTEGER
!>           On entry, LDB specifies the first dimension of B as declared
!>           in the calling (sub) program. When  TRANSB = 'N' or 'n' then
!>           LDB must be at least  max( 1, k ), otherwise  LDB must be at
!>           least  max( 1, n ).
!> 

BETA

!>          BETA is COMPLEX*16.
!>           On entry,  BETA  specifies the scalar  beta.  When  BETA  is
!>           supplied as zero then C need not be set on input.
!> 

C

!>          C is COMPLEX*16 array, dimension ( LDC, N )
!>           Before entry, the leading  n 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 upper or lower triangular part of the matrix
!>           C  is overwritten by the n by n matrix
!>           ( alpha*op( A )*op( B ) + beta*C ).
!> 

LDC

!>          LDC is INTEGER
!>           On entry, LDC specifies the first dimension of C as declared
!>           in  the  calling  (sub)  program.   LDC  must  be  at  least
!>           max( 1, n ).
!> 

Martin Koehler

!>
!>  Level 3 Blas routine.
!>
!>  -- Written on 19-July-2023.
!>     Martin Koehler, MPI Magdeburg
!>