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@jobliz
Created May 12, 2019 01:49
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Himmelblau function with simulated annealing
// gcc himmelblau_simulated_annealing.c -lm && ./a.out
#include <math.h>
#include <stdio.h>
#include <stdlib.h> // RAND_MAX
double rand01(void)
{
return rand() / ((double) RAND_MAX);
}
double hb(double x, double y) {
return pow(((pow(x,2))+y-11),2) + pow((x+(pow(y,2))-7),2);
}
int main(int argc, char *argv[])
{
double x0, y0, k, T0;
x0 = 2;
y0 = 1;
k = 0.1f;
T0 = 1000.0f;
double x1, y1;
int M, N;
M = 300;
N = 15;
double xt, yt;
double alpha = 0.85;
double z = hb(x0, y0);
double ran_x_1, ran_x_2, ran_y_1, ran_y_2;
double new_value, current_value;
double form;
for(int i=0; i < M; i++) {
for(int j=0; j < N; j++) {
yt = 0;
xt = 0;
ran_x_1 = rand01();
ran_x_2 = rand01();
ran_y_1 = rand01();
ran_y_2 = rand01();
if(ran_x_1 >= 0.5) {
x1 = k * ran_x_2;
} else {
x1 = -k * ran_x_2;
}
if(ran_y_1 >= 0.5) {
y1 = k * ran_y_2;
} else {
y1 = -k * ran_y_2;
}
xt = x0 + x1;
yt = y0 + y1;
new_value = hb(xt, yt);
current_value = hb(x0, y0);
form = 1.0 / exp((new_value - current_value) / T0);
if(new_value <= current_value) {
x0 = xt;
y0 = yt;
} else if(rand01() <= form) {
x0 = xt;
y0 = yt;
} else {
x0 = x0;
y0 = y0;
}
}
z = current_value;
T0 = alpha * T0;
}
printf("X is: %f\n", x0);
printf("Y is: %f\n", y0);
printf("Minimized value is: %f\n", z);
return 0;
}
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