+
+real count_to_kPa(real count) = fraction_to_kPa(count / 2047);
+
+typedef struct {
+ real m, b;
+ int m_i, b_i;
+} line_t;
+
+line_t best_fit(real[] values, int first, int last) {
+ real sum_x = 0, sum_x2 = 0, sum_y = 0, sum_xy = 0;
+ int n = last - first + 1;
+ real m, b;
+ int m_i, b_i;
+
+ for (int i = first; i <= last; i++) {
+ sum_x += i;
+ sum_x2 += i**2;
+ sum_y += values[i];
+ sum_xy += values[i] * i;
+ }
+ m = (n*sum_xy - sum_y*sum_x) / (n*sum_x2 - sum_x**2);
+ b = sum_y/n - m*(sum_x/n);
+ return (line_t) { m = m, b = b };
+}
+
+real count_to_altitude(real count) {
+ return pressure_to_altitude(count_to_kPa(count) * 1000);
+}
+
+real fraction_to_altitude(real frac) = pressure_to_altitude(fraction_to_kPa(frac) * 1000);
+
+int num_samples = 1024;
+
+real[num_samples] alt = { [n] = fraction_to_altitude(n/(num_samples - 1)) };
+
+int num_part = 128;
+int seg_len = num_samples / num_part;
+
+line_t [dim(alt) / seg_len] fit = {
+ [n] = best_fit(alt, n * seg_len, n * seg_len + seg_len - 1)
+};
+
+int[num_samples/seg_len + 1] alt_part;
+
+alt_part[0] = floor (fit[0].b + 0.5);
+alt_part[dim(fit)] = floor(fit[dim(fit)-1].m * dim(fit) * seg_len + fit[dim(fit)-1].b + 0.5);
+
+for (int i = 0; i < dim(fit) - 1; i++) {
+ real here, there;
+ here = fit[i].m * (i+1) * seg_len + fit[i].b;
+ there = fit[i+1].m * (i+1) * seg_len + fit[i+1].b;
+ alt_part[i+1] = floor ((here + there) / 2 + 0.5);
+}
+
+real count_to_fit_altitude(int count) {
+ int sub = count // seg_len;
+ int off = count % seg_len;
+ line_t l = fit[sub];
+ real r_v;
+ real i_v;
+
+ r_v = count * l.m + l.b;
+ i_v = (alt_part[sub] * (seg_len - off) + alt_part[sub+1] * off) / seg_len;
+ return i_v;
+}
+
+real max_error = 0;
+int max_error_count = 0;
+real total_error = 0;
+
+for (int count = 0; count < num_samples; count++) {
+ real kPa = fraction_to_kPa(count / (num_samples - 1));