SUBROUTINE MVMISG( TRANS, N, M, X, LDX, Y, LDY )
*     ..
*     .. Scalar Arguments ..
      INTEGER            LDY, LDX, M, N, TRANS
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   Y( LDY, * ), X( LDX, * )
*     ..
*
*  Purpose
*  =======
*
*  Compute
*
*               Y(:,1:M) = op(A)*X(:,1:M)
*
*  where op(A) is A or A' (the transpose of A). The A is the Ising 
*  matrix.
*
*  Arguments
*  =========
*
*  TRANS   (input) INTEGER
*          If TRANS = 0, compute Y(:,1:M) = A*X(:,1:M) 
*          If TRANS = 1, compute Y(:,1:M) = A'*X(:,1:M) 
*           
*  N       (input) INTEGER
*          The order of the matrix A. N has to be an even number.
*
*  M       (input) INTEGERS
*          The number of columns of X to multiply.
*
*  X       (input) DOUBLE PRECISION array, dimension ( LDX, M )
*          X contains the matrix (vectors) X.
*
*  LDX     (input) INTEGER
*          The leading dimension of array X, LDX >= max( 1, N )
*
*  Y       (output) DOUBLE PRECISION array, dimension (LDX, M )
*          contains the product of the matrix op(A) with X.
*
*  LDY     (input) INTEGER
*          The leading dimension of array Y, LDY >= max( 1, N )
*
*  ===================================================================
*