annealing parameters

Author: tsutaj

marathon/annealing_parameters.cpp

@@ -0,0 +1,27 @@
+template <int ITER_PERIOD = 1 << 20>
+struct AnnealingParameters {
+    const double start_temp;
+    const double end_temp;
+    double cur_temp;
+    double ln_p[ITER_PERIOD];
+    AnnealingParameters(double start_temp, double end_temp, Rand& rnd)
+        : start_temp(start_temp), end_temp(end_temp), cur_temp(start_temp) {
+        for(int i=0; i<ITER_PERIOD; i++) {
+            ln_p[i] = log(rnd.NextDouble());
+        }
+    }
+
+    inline void update_temp_linear(double ratio) {
+        cur_temp = start_temp + (end_temp - start_temp) * ratio;
+    }
+
+    inline void update_temp_pow(double ratio) {
+        cur_temp = start_temp * pow(end_temp / start_temp, ratio);
+    }
+
+    // p < exp(diff / temp) を変形すると、diff > temp * ln_p
+    // diff がこの値を超えていたら採用できる
+    inline bool is_acceptable(int iter, int diff) const {
+        return diff > cur_temp * ln_p[iter % ITER_PERIOD];
+    }
+};