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
+}