int main()
{
/* parameter vector */
int n_par = 3; // number of parameters in model function f
double par[3] = { 1, 0, 1 }; // relatively bad starting value
/* data pairs: slightly distorted standard parabola */
int m_dat = 11; // number of data pairs
int i;
double x[11] = { -5., -4., -3., -2., -1., 0., 1., 2., 3., 4., 5. };
double y[11] = { 25.5, 16.6, 9.9, 4.4, 1.1, 0, 1.1, 4.2, 9.3, 16.4, 25.5 };
/* auxiliary parameters */
lm_status_struct status;
lm_control_struct control = lm_control_double;
control.printflags = 3; // monitor status (+1) and parameters (+2)
/* perform the fit */
printf( "Fitting:\n" );
lmcurve_fit( n_par, par, m_dat, x, y, f, &control, &status );
/* print results */
printf( "\nResults:\n" );
printf( "status after %d function evaluations:\n %s\n",
status.nfev, lm_infmsg[status.info] );
printf("obtained parameters:\n");
for ( i = 0; i < n_par; ++i)
printf(" par[%i] = %12g\n", i, par[i]);
printf("obtained norm:\n %12g\n", status.fnorm );
printf("fitting data as follows:\n");
for ( i = 0; i < m_dat; ++i)
printf( " t[%2d]=%12g y=%12g fit=%12g residue=%12g\n",
i, x[i], y[i], f(x[i],par), y[i] - f(x[i],par) );
return 0;
}
int main()
{
/* initialize random number generator */
srand(1);
/* loop over random draws */
int iter;
for( iter=0; iter<100; ++iter ){
/* parameter vector */
int n_par = 8;
double ini[8], par[8];
int j;
for( j=0; j<n_par; ++j ){
ini[j] = 10. * rand()/RAND_MAX; /* to generate data */
par[j] = 10. * rand()/RAND_MAX; /* start values for fit */
}
/* data pairs */
int m_dat = 100; // number of data pairs
double t[100], y[100];
int i;
for( i=0; i<m_dat; ++i ){
/* time points chosen logarithmically spaced between 0.01 and 100 */
t[i] = exp( log(0.01)+log(100/0.01)*i/(m_dat-1) );
y[i] = f( t[i], ini );
}
/* auxiliary parameters */
lm_status_struct status;
lm_control_struct control = lm_control_double;
control.maxcall = 8000;
control.printflags = 0;
/* perform the fit */
lmcurve_fit( n_par, par, m_dat, t, y, f, &control, &status );
/* print results */
printf( "%2d %5d %18.11f\n", status.info, status.nfev, status.fnorm );
/*
printf( "status after %d function evaluations:\n %s\n",
status.nfev, lm_infmsg[status.info] );
printf("initial and fitted parameters:\n");
for ( i = 0; i < n_par; ++i)
printf(" par%i: %18.11f -> %18.11f\n", i, ini[i], par[i]);
printf("obtained norm:\n %12g\n", status.fnorm );
printf("fitting data as follows:\n");
for ( i = 0; i < m_dat; ++i)
printf( " t[%2d]=%12g y=%12g fit=%12g residue=%12g\n",
i, t[i], y[i], f(t[i],par), y[i] - f(t[i],par) );
*/
}
return 0;
}
