#include "mex.h"

 void rosenbrock(double x[], double cof, double *j1, double grad[])
 {
   double t1, t2;
   t1 = x[1] - x[0]*x[0]; t2 = 1e0 - x[0]; 
   *j1 = cof*t1*t1 + t2*t2;
   grad[0] = -4e0*cof*x[0]*t1 - 2e0*t2;
   grad[1] = 2e0*cof*t1;
   return;
 }

/* The gateway function. */
 void mexFunction(
   int nlhs, mxArray *plhs[],
   int nrhs, const mxArray *prhs[])
   {
     int n, m;
     double *x, cof, *j1, *grad;

/* Check for proper number of arguments */
     if (nrhs !=2)
       mexErrMsgTxt("Two inputs required.");
     else if (nlhs != 2)
       mexErrMsgTxt("Only two outputs is allowed.");
     else if (!mxIsNumeric(prhs[0]) || !mxIsNumeric(prhs[1]))
       mexErrMsgTxt("One of the inputs not numeric.");

/* Create a pointer to a copy of the first input, vector x. */
     x = mxGetPr(prhs[0]);

/* Get the dimensions of the matrix input a. */
     n = mxGetN(prhs[0]);
     m = mxGetM(prhs[0]);

/* Create a scalar copy of the second input. */
     cof = mxGetScalar(prhs[1]);

/* Create the outputs j1 and grad. */
     plhs[0] = mxCreateDoubleMatrix(1,1,mxREAL);
     j1 = mxGetPr(plhs[0]);
     plhs[1] = mxCreateDoubleMatrix(m,n,mxREAL);
     grad = mxGetPr(plhs[1]);

/* Compute the outputs using C subroutine. */
     rosenbrock(x,cof,j1,grad);

   }