sub and mag

govector_test.go

@@ -0,0 +1,29 @@
+package govector
+
+import (
+	// "fmt"
+	"testing"
+)
+
+func TestSub(t *testing.T) {
+	p1 := point2d{10, 10}
+	p2 := point2d{5, 5}
+
+	v := p1.sub(p2)
+
+	if v != (vector2d{5, 5}) {
+		t.Errorf("Sub Error")
+	}
+}
+
+func TestMag(t *testing.T) {
+	p1 := point2d{10, 10}
+	p2 := point2d{7, 6}
+
+	v := p1.sub(p2)
+	m := v.mag()
+
+	if m != 5 {
+		t.Errorf("Mag Error")
+	}
+}

vectorpoint.go

@@ -0,0 +1,26 @@
+package govector
+
+import (
+    "math"
+)
+
+type vector2d struct {
+	X float64 `json:"x"`
+	Y float64 `json:"y"`
+}
+
+type point2d struct {
+	X float64 `json:"x"`
+	Y float64 `json:"y"`
+}
+
+const epsilon = 1e-7
+
+func (p1 point2d) sub(p2 point2d) vector2d {
+	v := vector2d{p1.X - p2.X, p1.Y - p2.Y}
+	return v
+}
+
+func (v vector2d) mag() float64 {
+	return math.Abs(math.Sqrt(v.X*v.X + v.Y*v.Y))
+}