Merge pull request #47 from spakin/master

🐛 CrossUniformFloat64 should preserve total values

crossover.go

@@ -15,8 +15,10 @@ import (
 func CrossUniformFloat64(p1 []float64, p2 []float64, rng *rand.Rand) {
 	for i := range p1 {
 		var p = rng.Float64()
-		p1[i] = p*p1[i] + (1-p)*p2[i]
-		p2[i] = (1-p)*p1[i] + p*p2[i]
+		var o1 = p*p1[i] + (1-p)*p2[i]
+		var o2 = (1-p)*p1[i] + p*p2[i]
+		p1[i] = o1
+		p2[i] = o2
 	}
 }
 

crossover_test.go

@@ -37,6 +37,14 @@ func TestCrossUniformFloat64(t *testing.T) {
 			t.Error("New values are not contained in hyper-rectangle")
 		}
 	}
+	// Check that each parent sum equals the offspring sum
+	for i := 0; i < len(p1); i++ {
+		pSum := p1[i] + p2[i]
+		oSum := o1[i] + o2[i]
+		if math.Abs(pSum-oSum) > 1e-14 {
+			t.Errorf("Total value is not preserved from parents to offsprings (%v vs. %v)", pSum, oSum)
+		}
+	}
 }
 
 func TestGNX(t *testing.T) {

ga_test.go

@@ -240,7 +240,7 @@ func TestGALog(t *testing.T) {
 	ga.init(NewVector)
 	ga.evolve()
 	var expected = "pop_id=QrZ min=-21.342844 max=16.086140 avg=-2.554992 std=11.673396\n" +
-		"pop_id=QrZ min=-29.052226 max=10.630133 avg=-11.885364 std=8.266295\n"
+		"pop_id=QrZ min=-29.052226 max=10.630133 avg=-12.575381 std=8.436837\n"
 	if s := b.String(); s != expected {
 		t.Errorf("Expected %s, got %s", expected, s)
 	}