#include "mex.h"

/*
 * timestwo.c - example found in API guide
 *
 * Computational function that takes a scalar and double it.
 *
 * This is a MEX-file for MATLAB.
 * Copyright 1984-2000 The MathWorks, Inc.
 */
 
/* $Revision: 1.8 $ */

void timestwo(double y[], double x[])
{
  y[0] = 2.0*x[0];
}

void mexFunction( int nlhs, mxArray *plhs[],
                  int nrhs, const mxArray *prhs[] )
{
  double *x,*y;
  int     mrows,ncols;
  
  /* Check for proper number of arguments. */
  if(nrhs!=1) {
    mexErrMsgTxt("One input required.");
  } else if(nlhs>1) {
    mexErrMsgTxt("Too many output arguments");
  }
  
  /* The input must be a noncomplex scalar double.*/
  mrows = mxGetM(prhs[0]);
  ncols = mxGetN(prhs[0]);
  if( !mxIsDouble(prhs[0]) || mxIsComplex(prhs[0]) ||
      !(mrows==1 && ncols==1) ) {
    mexErrMsgTxt("Input must be a noncomplex scalar double.");
  }
  
  /* Create matrix for the return argument. */
  plhs[0] = mxCreateDoubleMatrix(mrows,ncols, mxREAL);
  
  /* Assign pointers to each input and output. */
  x = mxGetPr(prhs[0]);
  y = mxGetPr(plhs[0]);
  
  /* Call the timestwo subroutine. */
  timestwo(y,x);
}