ozone_cp/APP/least_square_method.c

#include <stdbool.h>
#include <stdint.h>
#include "least_square_method.h"
void least_square_method(int xstart, int xtedp, int xend, gety_t gety, float *c, float *k) {
  double xi = 0, x2 = 0, yi = 0, xy = 0;
  int xnow = 0;
  int maxn = 0;
  for (xnow = xstart; xnow <= xend; xnow += xtedp) {
    xi += xnow, x2 += xnow * xnow, yi += gety(xnow), xy += xnow * gety(xnow);
    maxn++;
  }
  *c = (yi * x2 - xy * xi) / (x2 * maxn - xi * xi);
  *k = (yi * xi - xy * maxn) / (xi * xi - x2 * maxn);
}