]> git.sesse.net Git - foosball/blobdiff - foosrank.cpp
Remove an obsolete if.
[foosball] / foosrank.cpp
index b4f12dc927f2371e03769e2d279eb9fd0505c14c..22ade74c7c78f8c831d0c0e668d0f58a251fb739 100644 (file)
@@ -16,11 +16,6 @@ static const double int_step_size = 75.0;
 // rating constant (see below)
 static const double rating_constant = 455.0;
 
-#if USE_LOGISTIC_DISTRIBUTION
-// constant used in the logistic pdf
-static const double l_const = M_PI / (2.0 * sqrt(3.0));
-#endif
-
 using namespace std;
 
 static double prob_score_real(int k, int a, double binomial, double rd_norm);
@@ -149,8 +144,7 @@ static void compute_opponent_rating_pdf(int k, int a, double mu2, double sigma2,
                // opponent's pdf
 #if USE_LOGISTIC_DISTRIBUTION
                double z = (x1 - mu2) * invsigma2;
-               double ch = cosh(l_const * z);
-               func1[i].real() = 1.0 / (ch * ch);
+               func1[i].real() = sech2(0.5 * z);
 #else
                double z = (x1 - mu2) * invsq2sigma2;
                func1[i].real() = exp(-z*z);
@@ -316,11 +310,11 @@ static void least_squares(vector<pair<double, double> > &curve, double mu1, doub
 
 #if USE_LOGISTIC_DISTRIBUTION
                        // df/dA(x_i)
-                       matA[i + 0 * curve.size()] = sech2(l_const * (x-mu)/sigma);
+                       matA[i + 0 * curve.size()] = sech2(0.5 * (x-mu)/sigma);
 
                        // df/dµ(x_i)
-                       matA[i + 1 * curve.size()] = 2.0 * l_const * A * matA[i + 0 * curve.size()]
-                               * tanh(l_const * (x-mu)/sigma) / sigma;
+                       matA[i + 1 * curve.size()] = A * matA[i + 0 * curve.size()]
+                               * tanh(0.5 * (x-mu)/sigma) / sigma;
 
                        // df/dσ(x_i)
                        matA[i + 2 * curve.size()] = 
@@ -346,7 +340,7 @@ static void least_squares(vector<pair<double, double> > &curve, double mu1, doub
                        double y = curve[i].second;
 
 #if USE_LOGISTIC_DISTRIBUTION
-                       dbeta[i] = y - A * sech2(l_const * (x-mu)/sigma);
+                       dbeta[i] = y - A * sech2(0.5 * (x-mu)/sigma);
 #else
                        dbeta[i] = y - A * exp(- (x-mu)*(x-mu)/(2.0*sigma*sigma));
 #endif
@@ -389,27 +383,27 @@ static void compute_new_rating(double mu1, double sigma1, double mu2, double sig
                // my pdf
                double z = (r1 - mu1) / sigma1;
 #if USE_LOGISTIC_DISTRIBUTION
-               double ch = cosh(l_const * z);
-               curve[i].second /= (ch * ch);
+               curve[i].second *= sech2(0.5 * z);
 #else
                double gaussian = exp(-(z*z/2.0));
                curve[i].second *= gaussian;
 #endif
        }
-
+       
        // Compute the overall probability of the given result, by integrating
        // the entire resulting pdf. Note that since we're actually evaluating
        // a double integral, we'll need to multiply by h² instead of h.
-       // (For some reason, Simpson's rule gives markedly worse accuracy here.
-       // Probably related to h² somehow?)
        {
                double h = (curve.back().first - curve.front().first) / (curve.size() - 1);
-               double sum = 0.0;
-               for (unsigned i = 0; i < curve.size(); ++i) {
-                       sum += curve[i].second;
+               double sum = curve.front().second;
+               for (unsigned i = 1; i < curve.size() - 1; i += 2) {
+                       sum += 4.0 * curve[i].second;
                }
-
-               sum *= h * h;
+               for (unsigned i = 2; i < curve.size() - 1; i += 2) {
+                       sum += 2.0 * curve[i].second;
+               }
+               sum += curve.back().second;
+               sum *= h * h / 3.0;
        
                // FFT convolution multiplication factor (FFTW computes unnormalized
                // transforms)
@@ -417,8 +411,8 @@ static void compute_new_rating(double mu1, double sigma1, double mu2, double sig
 
                // pdf normalization factors
 #if USE_LOGISTIC_DISTRIBUTION
-               sum *= M_PI / (sigma1 * 4.0 * sqrt(3.0));
-               sum *= M_PI / (sigma2 * 4.0 * sqrt(3.0));
+               sum /= (sigma1 * 4.0);
+               sum /= (sigma2 * 4.0);
 #else
                sum /= (sigma1 * sqrt(2.0 * M_PI));
                sum /= (sigma2 * sqrt(2.0 * M_PI));
@@ -468,7 +462,7 @@ static void compute_new_double_rating(double mu1, double sigma1, double mu2, dou
 
 #if USE_LOGISTIC_DISTRIBUTION
                        double z = (r2 - mu2) * invsigma2;
-                       double gaussian = sech2(l_const * z);
+                       double gaussian = sech2(0.5 * z);
 #else  
                        double z = (r2 - mu2) * invsq2sigma2;
                        double gaussian = exp(-z*z);
@@ -478,7 +472,7 @@ static void compute_new_double_rating(double mu1, double sigma1, double mu2, dou
 
 #if USE_LOGISTIC_DISTRIBUTION
                double z = (r1 - mu1) / sigma1;
-               double gaussian = sech2(l_const * z);
+               double gaussian = sech2(0.5 * z);
 #else
                double z = (r1 - mu1) / sigma1;
                double gaussian = exp(-(z*z/2.0));
@@ -491,16 +485,18 @@ static void compute_new_double_rating(double mu1, double sigma1, double mu2, dou
        // a triple integral, we'll need to multiply by 4h³ (no idea where the
        // 4 factor comes from, probably from the 0..6000 range somehow) instead
        // of h.
-       // (TODO: Evaluate Simpson's rule here, although it's probably even worse
-       // than for the single case.)
        {
                double h = (newcurve.back().first - newcurve.front().first) / (newcurve.size() - 1);
-               double sum = 0.0;
-               for (unsigned i = 0; i < newcurve.size(); ++i) {
-                       sum += newcurve[i].second;
+               double sum = newcurve.front().second;
+               for (unsigned i = 1; i < newcurve.size() - 1; i += 2) {
+                       sum += 4.0 * newcurve[i].second;
                }
+               for (unsigned i = 2; i < newcurve.size() - 1; i += 2) {
+                       sum += 2.0 * newcurve[i].second;
+               }
+               sum += newcurve.back().second;
 
-               sum *= 4.0 * h * h * h;
+               sum *= 4.0 * h * h * h / 3.0;
        
                // FFT convolution multiplication factor (FFTW computes unnormalized
                // transforms)
@@ -508,9 +504,9 @@ static void compute_new_double_rating(double mu1, double sigma1, double mu2, dou
 
                // pdf normalization factors
 #if USE_LOGISTIC_DISTRIBUTION
-               sum *= M_PI / (sigma1 * 4.0 * sqrt(3.0));
-               sum *= M_PI / (sigma2 * 4.0 * sqrt(3.0));
-               sum *= M_PI / (sigma_t * 4.0 * sqrt(3.0));
+               sum /= (sigma1 * 4.0);
+               sum /= (sigma2 * 4.0);
+               sum /= (sigma_t * 4.0);
 #else
                sum /= (sigma1 * sqrt(2.0 * M_PI));
                sum /= (sigma2 * sqrt(2.0 * M_PI));
@@ -548,18 +544,14 @@ int main(int argc, char **argv)
                int score2 = atoi(argv[10]);
                double mu, sigma, probability;
                compute_new_double_rating(mu1, sigma1, mu2, sigma2, mu3, sigma3, mu4, sigma4, score1, score2, mu, sigma, probability);
-               if (score1 > score2) {
-                       printf("%f %f %f\n", mu, sigma, probability);
-               } else {
-                       printf("%f %f %f\n", mu, sigma, probability);
-               }
+               printf("%f %f %f\n", mu, sigma, probability);
        } else if (argc > 8) {
                double mu3 = atof(argv[5]);
                double sigma3 = atof(argv[6]);
                double mu4 = atof(argv[7]);
                double sigma4 = atof(argv[8]);
                int k = atoi(argv[9]);
-       
+
                // assess all possible scores
                for (int i = 0; i < k; ++i) {
                        double newmu1_1, newmu1_2, newmu2_1, newmu2_2;
@@ -592,11 +584,7 @@ int main(int argc, char **argv)
                double mu, sigma, probability;
                compute_new_rating(mu1, sigma1, mu2, sigma2, score1, score2, mu, sigma, probability);
 
-               if (score1 > score2) {
-                       printf("%f %f %f\n", mu, sigma, probability);
-               } else {
-                       printf("%f %f %f\n", mu, sigma, probability);
-               }
+               printf("%f %f %f\n", mu, sigma, probability);
        } else {
                int k = atoi(argv[5]);