Added two test cases from sublee/trueskill.

src/factor_graph.rs

@@ -1,4 +1,5 @@
 use std::collections::HashMap;
+use std::f64;
 
 use gaussian::Gaussian;
 use math;
@@ -71,6 +72,8 @@ impl Variable {
 
         self.value = value;
 
+        debug!("Variable::value old={:?}, new={:?}", old, value);
+
         delta
     }
 
@@ -83,6 +86,8 @@ impl Variable {
 
         self.factors.insert(factor, message);
         self.value = self.value / old * message;
+
+        debug!("Variable::message old={:?}, new={:?}", old, message);
     }
 
     pub fn get_message(&self, factor: usize) -> Gaussian {
@@ -229,14 +234,16 @@ impl SumFactor {
         fy: Vec<Gaussian>,
         a: &[f64],
     ) {
-        let (sum_pi, sum_tau) =
-            a.iter()
-                .zip(y.iter().zip(fy.iter()))
-                .fold((0.0, 0.0), |(pi, tau), (a, (y, fy))| {
-                    let x = *y / *fy;
+        let (sum_pi, sum_tau) = a.iter()
+            .zip(y.iter().zip(fy.iter()))
+            .fold((0.0, 0.0f64), |(pi, tau), (a, (y, fy))| {
+                let x = *y / *fy;
 
-                    (pi + a.powi(2) / x.pi(), tau + a * x.tau() / x.pi())
-                });
+                let new_pi = a.powi(2) / x.pi();
+                let new_tau = a * x.mu();
+
+                (pi + new_pi, tau + new_tau)
+            });
 
         let new_pi = 1.0 / sum_pi;
         let new_tau = new_pi * sum_tau;
@@ -278,12 +285,10 @@ impl SumFactor {
             .coeffs
             .iter()
             .enumerate()
-            .map(|(i, coeff)| {
-                if i == index {
-                    1.0 / idx_coeff
-                } else {
-                    -coeff / idx_coeff
-                }
+            .map(|(i, coeff)| if i == index {
+                1.0 / idx_coeff
+            } else {
+                -coeff / idx_coeff
             })
             .collect::<Vec<_>>();