Split out maths functions into maths, vector and bearing

pkg/maths/maths.go

@@ -0,0 +1,41 @@
+package maths
+
+// Abs gets the absolute value of an int
+func Abs(x int) int {
+	if x < 0 {
+		return -x
+	}
+	return x
+}
+
+// pmod is a mositive modulo
+// golang's % is a "remainder" function si misbehaves for negative modulus inputs
+func Pmod(x, d int) int {
+	if x == 0 || d == 0 {
+		return 0
+	}
+	x = x % d
+	if x >= 0 {
+		return x
+	} else if d < 0 {
+		return x - d
+	} else {
+		return x + d
+	}
+}
+
+// Max returns the highest int
+func Max(x int, y int) int {
+	if x < y {
+		return y
+	}
+	return x
+}
+
+// Min returns the lowest int
+func Min(x int, y int) int {
+	if x > y {
+		return y
+	}
+	return x
+}

pkg/maths/maths_test.go

@@ -0,0 +1,33 @@
+package maths
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAbs(t *testing.T) {
+	assert.Equal(t, 0, Abs(0))
+	assert.Equal(t, 1, Abs(1))
+	assert.Equal(t, 1, Abs(-1))
+}
+
+func TestPmod(t *testing.T) {
+	assert.Equal(t, 0, Pmod(0, 0))
+	assert.Equal(t, 2, Pmod(6, 4))
+	assert.Equal(t, 2, Pmod(-6, 4))
+	assert.Equal(t, 4, Pmod(-6, 10))
+}
+
+func TestMax(t *testing.T) {
+	assert.Equal(t, 500, Max(100, 500))
+	assert.Equal(t, 1, Max(-4, 1))
+	assert.Equal(t, -2, Max(-4, -2))
+}
+
+func TestMin(t *testing.T) {
+	assert.Equal(t, 100, Min(100, 500))
+	assert.Equal(t, -4, Min(-4, 1))
+	assert.Equal(t, -4, Min(-4, -2))
+
+}