#pragma once

#include <gsl/gsl_matrix.h>
#include <gsl/gsl_rng.h>

/* Parameters for bivariate
 * gaussian PDF
 */
struct par {
  double x0;       // x mean
  double y0;       // y mean
  double sigma_x;  // x standard dev
  double sigma_y;  // y standard dev
  double rho;      // correlation: cov(x,y)/σx⋅σy
};


/* A sample of N 2D points is an
 * N×2 matrix, with vectors as rows.
 */
typedef struct {
  struct par p;
  gsl_matrix *data;
} sample_t;


/* Create a sample of `n` points */
sample_t* sample_t_alloc(size_t n, struct par p);


/* Delete a sample */
void sample_t_free(sample_t *x);


/* `generate_normal(r, n, p)` will create
 * a sample of `n` points, distributed
 * according to a bivariate gaussian distribution
 * of parameters `p`.
 */
sample_t* generate_normal(gsl_rng *r, size_t n, struct par *p);