# include "mex.h"

void mexFunction ( int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[] );

//****************************************************************************80

void mexFunction ( int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[] )

//****************************************************************************80
//
//  Purpose:
//
//    MEXFUNCTION is a MATLAB/C++ interface for the factorial function.
//
//  Discussion:
//
//    This file should be called "fact.cpp".  It should be placed in the
//    MATLAB user's path.  It can either be compiled externally, with
//    a command like
//
//      mex fact.cpp
//
//    creating a compiled MEX file, or, inside of MATLAB, the command
//
//      mex fact.cpp
//
//    accomplishes the same task.  Once the file has been compiled,
//    The MATLAB user can invoke the function by typing:
//
//      y = fact ( x )
//
//    The routine carries out the computation of the factorial of X,
//    whose value is returned in Y.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license.
//
//  Modified:
//
//    28 September 2013
//
//  Author:
//
//    Duane Hanselman and Bruce Littlefield
//
//  Reference:
//
//    Duane Hanselman, Bruce Littlefield,
//    Mastering MATLAB 7,
//    Pearson Prentice Hall, 2005,
//    ISBN: 0-13-143018-1.
//
//    The Mathworks,
//    MATLAB External Interfaces,
//    The Mathworks, 2000.
//
//  Parameters:
//
//    Input, int NLHS, the number of output arguments.
//
//    Input, mxArray *PLHS[NLHS], pointers to the output arguments.
//
//    Input, int NRHS, the number of input arguments.
//
//    Input, const mxArray *PRHS[NRHS], pointers to the input arguments.
//
{
  int i;
  double x;
  double y;
  double *y_pointer;
//
//  INPUT:
//    Retrieve the (first) (scalar) input argument from the line
//
//    y = fact ( x )
//
  x = mxGetScalar ( prhs[0] );
//
//  COMPUTATION:
//    Here is where the computation is done.
//    In many cases, it would make sense to have this computation be in
//    separate C++ function, so that the mexFunction is really just an
//    interface.
//
  y = 1.0;
  for ( i = 1; i <= ( int ) x; i++ )
  {
    y = y * ( double ) i;
  }
//
//  OUTPUT:
//    Make space for the output argument,
//    retrieve the value of the pointer to that space,
//    and copy the value of Y into the address for the output.
//
  plhs[0] = mxCreateDoubleMatrix ( 1, 1, mxREAL );

  y_pointer = mxGetPr ( plhs[0] );

  *y_pointer = y;

  return;
}