subroutine cher2 ( uplo, n, alpha, x, incx, y, incy, a, lda )
*     .. scalar arguments ..
      complex            alpha
      integer            incx, incy, lda, n
      character*1        uplo
*     .. array arguments ..
      complex            a( lda, * ), x( * ), y( * )
*     ..
*
*  purpose
*  =======
*
*  cher2  performs the hermitian rank 2 operation
*
*     a := alpha*x*conjg( y' ) + conjg( alpha )*y*conjg( x' ) + a,
*
*  where alpha is a scalar, x and y are n element vectors and a is an n
*  by n hermitian matrix.
*
*  parameters
*  ==========
*
*  uplo   - character*1.
*           on entry, uplo specifies whether the upper or lower
*           triangular part of the array a is to be referenced as
*           follows:
*
*              uplo = 'u' or 'u'   only the upper triangular part of a
*                                  is to be referenced.
*
*              uplo = 'l' or 'l'   only the lower triangular part of a
*                                  is to be referenced.
*
*           unchanged on exit.
*
*  n      - integer.
*           on entry, n specifies the order of the matrix a.
*           n must be at least zero.
*           unchanged on exit.
*
*  alpha  - complex         .
*           on entry, alpha specifies the scalar alpha.
*           unchanged on exit.
*
*  x      - complex          array of dimension at least
*           ( 1 + ( n - 1 )*abs( incx ) ).
*           before entry, the incremented array x must contain the n
*           element vector x.
*           unchanged on exit.
*
*  incx   - integer.
*           on entry, incx specifies the increment for the elements of
*           x. incx must not be zero.
*           unchanged on exit.
*
*  y      - complex          array of dimension at least
*           ( 1 + ( n - 1 )*abs( incy ) ).
*           before entry, the incremented array y must contain the n
*           element vector y.
*           unchanged on exit.
*
*  incy   - integer.
*           on entry, incy specifies the increment for the elements of
*           y. incy must not be zero.
*           unchanged on exit.
*
*  a      - complex          array of dimension ( lda, n ).
*           before entry with  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. on exit, the
*           upper triangular part of the array a is overwritten by the
*           upper triangular part of the updated matrix.
*           before entry with 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. on exit, the
*           lower triangular part of the array a is overwritten by the
*           lower triangular part of the updated matrix.
*           note that the imaginary parts of the diagonal elements need
*           not be set, they are assumed to be zero, and on exit they
*           are set to zero.
*
*  lda    - integer.
*           on entry, lda specifies the first dimension of a as declared
*           in the calling (sub) program. lda must be at least
*           max( 1, n ).
*           unchanged on exit.
*
*
*  level 2 blas routine.
*
*  -- written on 22-october-1986.
*     jack dongarra, argonne national lab.
*     jeremy du croz, nag central office.
*     sven hammarling, nag central office.
*     richard hanson, sandia national labs.
*