int
main (void)
{
const gsl_rng_type * T;
gsl_rng * r;
gsl_histogram2d * h = gsl_histogram2d_alloc (10, 10);
gsl_histogram2d_set_ranges_uniform (h,
0.0, 1.0,
0.0, 1.0);
gsl_histogram2d_accumulate (h, 0.3, 0.3, 1);
gsl_histogram2d_accumulate (h, 0.8, 0.1, 5);
gsl_histogram2d_accumulate (h, 0.7, 0.9, 0.5);
gsl_rng_env_setup ();
T = gsl_rng_default;
r = gsl_rng_alloc (T);
{
int i;
gsl_histogram2d_pdf * p
= gsl_histogram2d_pdf_alloc (h->nx, h->ny);
gsl_histogram2d_pdf_init (p, h);
for (i = 0; i < 1000; i++) {
double x, y;
double u = gsl_rng_uniform (r);
double v = gsl_rng_uniform (r);
gsl_histogram2d_pdf_sample (p, u, v, &x, &y);
printf ("%g %g\n", x, y);
}
gsl_histogram2d_pdf_free (p);
}
gsl_histogram2d_free (h);
gsl_rng_free (r);
return 0;
}
void
test2d_resample (void)
{
size_t i, j;
int status = 0;
double total = 0;
size_t N = 200000;
gsl_histogram2d *h;
gsl_ieee_env_setup ();
h = gsl_histogram2d_calloc_uniform (10, 10, 0.0, 1.0, 0.0, 1.0);
for (i = 0; i < 10; i++)
{
for (j = 0; j < 10; j++)
{
double w = 10.0 * i + j;
total += w;
gsl_histogram2d_accumulate (h, 0.1 * i, 0.1 * i, w);
}
}
{
gsl_histogram2d_pdf *p = gsl_histogram2d_pdf_alloc (10,10);
gsl_histogram2d *hh = gsl_histogram2d_calloc_uniform (20, 20,
0.0, 1.0,
0.0, 1.0);
gsl_histogram2d_pdf_init (p, h);
for (i = 0; i < N; i++)
{
double u = urand();
double v = urand();
double x, y;
status = gsl_histogram2d_pdf_sample (p, u, v, &x, &y);
status = gsl_histogram2d_increment (hh, x, y);
}
status = 0;
for (i = 0; i < 20; i++)
{
for (j = 0; j < 20; j++)
{
double z = 4 * total * gsl_histogram2d_get (hh, i, j) / (double) N;
size_t k1, k2;
double ya;
double x, xmax, y, ymax;
gsl_histogram2d_get_xrange (hh, i, &x, &xmax);
gsl_histogram2d_get_yrange (hh, j, &y, &ymax);
gsl_histogram2d_find (h, x, y, &k1, &k2);
ya = gsl_histogram2d_get (h, k1, k2);
if (ya == 0)
{
if (z != 0)
{
status = 1;
printf ("(%d,%d): %g vs %g\n", (int)i, (int)j, z, ya);
}
}
else
{
double err = 1 / sqrt (gsl_histogram2d_get (hh, i, j));
double sigma = fabs ((z - ya) / (ya * err));
if (sigma > 3)
{
status = 1;
printf ("%g vs %g err=%g sigma=%g\n", z, ya, err, sigma);
}
}
}
}
gsl_histogram2d_pdf_free (p) ;
gsl_histogram2d_free (hh) ;
gsl_test (status, "gsl_histogram2d_pdf_sample within statistical errors");
}
gsl_histogram2d_free (h) ;
}