#include <R.h>
#include <Rinternals.h>

void lorenz(size_t n, double t, double *y, double *dydt, void *data) {
  SEXP r_pars = (SEXP) data;
  double *pars = REAL(r_pars);
  double sigma = pars[0];
  double R = pars[1];
  double b = pars[2];
  dydt[0] = sigma * (y[1] - y[0]);
  dydt[1] = R * y[0] - y[1] - y[0] * y[2];
  dydt[2] = -b * y[2] + y[0] * y[1];
}