new name for arm:

multi-path ray-tracer radio medium (mrm)

tools/cooja/apps/mrm/java/statistics/Gaussian.java

@@ -0,0 +1,63 @@
+package statistics;
+
+// Gaussian CDF Taylor approximation
+// Code borrowed from http://www.cs.princeton.edu/introcs/21function/Gaussian.java.html 19/9 2006
+
+/*************************************************************************
+*  Compilation:  javac Gaussian.java
+*  Execution:    java Gaussian x mu sigma
+*
+*  Function to compute the Gaussian pdf (probability density function)
+*  and the Gaussian cdf (cumulative density function)
+*
+*  % java Gaussian 820 1019 209
+*  0.17050966869132111
+*
+*  % java Gaussian 1500 1019 209
+*  0.9893164837383883
+*
+*  % java Gaussian 1500 1025 231
+*  0.9801220907365489
+*
+*************************************************************************/
+
+public class Gaussian {
+
+ // return phi(x) = standard Gaussian pdf
+ public static double phi(double x) {
+     return Math.exp(-x*x / 2) / Math.sqrt(2 * Math.PI);
+ }
+
+ // return phi(x) = Gaussian pdf with mean mu and stddev sigma
+ public static double phi(double x, double mu, double sigma) {
+     return phi((x - mu) / sigma) / sigma;
+ }
+
+ // return Phi(z) = standard Gaussian cdf using Taylor approximation
+ public static double Phi(double z) {
+     if (z < -8.0) return 0.0;
+     if (z >  8.0) return 1.0;
+     double sum = 0.0, term = z;
+     for (int i = 3; sum + term != sum; i += 2) {
+         sum  = sum + term;
+         term = term * z * z / i;
+     }
+     return 0.5 + sum * phi(z);
+ }
+
+
+
+ // return Phi(z, mu, sigma) = Gaussian cdf with mean mu and stddev sigma
+ public static double Phi(double z, double mu, double sigma) {
+     return Phi((z - mu) / sigma);
+ } 
+
+
+ public static void main(String[] args) {
+     double z     = Double.parseDouble(args[0]);
+     double mu    = Double.parseDouble(args[1]);
+     double sigma = Double.parseDouble(args[2]);
+     System.out.println(Phi(z, mu, sigma));
+ }
+
+}