/* Change this to reflect the apropriate header file */
#include <math.h> 
#include "c:\matlab6p1\extern\include\mex.h"
// #include "c:\matlabr12\extern\include\mex.h"
// #include "c:\matlabr11\extern\include\mex.h"

/*
* garchcore.c - 
* This is a helper function and is part of the UCSD_GARCH toolbox 
* You can compile it and should work on any platform.
* 
* Author: Kevin Sheppard
* kksheppard@ucsd.edu
* Revision: 2    Date: 12/31/2001
*/
void makeh(double *data, double *parameters, int p, int q, int m, int T, double *covEst, double *Ht)
{
	int i, j;
	for (j=0; j<m; j++) {
		*(Ht+j)=*covEst;
	}
	for (i=m; i<T; i++) {
		*(Ht+i)=parameters[0];
		for (j=0; j<p; j++) {
			*(Ht+i)=*(Ht+i)+parameters[j+1]* pow(*(data+(i-(j+1))),2);
		}
        for (j=0; j<q; j++) {
			*(Ht+i)=*(Ht+i)+parameters[j+p+1]* *(Ht+(i-(j+1)));
		}
 	}
}


/* The gateway routine */
void mexFunction( int nlhs, mxArray *plhs[],
				 int nrhs, const mxArray *prhs[])
{
	double *data, *parameters, *Ht, *covEst;
	int p, q, m, T;
	int     mrows,ncols;
	
	/*  Check for proper number of arguments. */
	if(nrhs!=7) 
		mexErrMsgTxt("Seven inputs required.");
	if(nlhs!=1) 
		mexErrMsgTxt("One output required.");
	
	/*  Get the scalar inputs */
	p = mxGetScalar(prhs[3]);
	q = mxGetScalar(prhs[4]);
	m = mxGetScalar(prhs[5]);
	T = mxGetScalar(prhs[6]);
    
	/*  Create a pointer to the input matrices . */
	data           = mxGetPr(prhs[0]);
	parameters     = mxGetPr(prhs[1]);
	covEst         = mxGetPr(prhs[2]);
	
	/*  Get the dimensions of the matrix input ht to make an output matrix. */
	mrows = mxGetM(prhs[0]);
	ncols = mxGetN(prhs[0]);
	
	/*  Set the output pointer to the output matrix. */
	plhs[0] = mxCreateDoubleMatrix(mrows,ncols, mxREAL);
	
	/*  Create a C pointer to a copy of the output matrix. */
	Ht = mxGetPr(plhs[0]);
	
	/*  Call the C subroutine. */
	makeh(data,parameters,p, q, m, T, covEst, Ht);
	
}