// nonlinear_fit_test.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <lsfit.h>
#include <odesolver.h>
#include <autogk.h>
#include <ap.h>

int _tmain(int argc, _TCHAR* argv[])
{
    int m;
    int n;
    int k;
    ap::real_1d_array y;
    ap::real_2d_array x;
    ap::real_1d_array c;
    lsfitreport rep;
    lsfitstate state;
    int info;
    double epsf;
    double epsx;
    int maxits;
    int i;
    int j;
    n = 1000;
    m = 1;
    k = 3;
    y.setlength(n);
    x.setlength(n, m);
    c.setlength(k);
	// formula: asy - a * exp(-b * x);
    for(i = 0; i <= n-1; i++)
    {
        x(i,0) = 10.0 * ap::randomreal() - 5.0; // from -5 to 5
        y(i) = 12.0 - 4.0 * exp(-0.5 * x(i,0)); // asy = 12, a = 4.0, b = 0.5
    }
    c(0) = 5.0;
	c(1) = 2.0;
	c(2) = 5.5;
    epsf = 0.000002;
    epsx = 0.0000000001;
    maxits = 0;
    
    lsfitnonlinearfg(x, y, c, n, m, k, epsf, epsx, maxits, true, state);
	    while(lsfitnonlineariteration(state))
    {
		double asy = state.c(0);
		double a = state.c(1);
		double b = state.c(2);
		double x = state.x(0);
        if( state.needf )
        {
            state.f = asy - a * exp(-b * x);
        }
        if( state.needfg )
        {
            state.f = asy - a * exp(-b * x);
            state.g(0) = 1.0;
			state.g(1) = -exp(-b * x);
			state.g(2) = -a * x * state.g(1);
        }
    }
    lsfitnonlinearresults(state, info, c, rep);
    printf("asy %0.10lf, a %0.10lf, b %0.10lf\n",
        double(c(0)),
		double(c(1)),
		double(c(2))
		);
    printf("rms.err: %0.3lf\n",
        double(rep.rmserror));
    printf("max.err: %0.3lf\n",
        double(rep.maxerror));
    printf("Termination type: %0ld\n",
        long(info));
    printf("\n\n");
};