Trig functions (#29)

src/measure/__test__/mathTests.ts

@@ -1,4 +1,5 @@
-import { meters, seconds } from "../../unit/base";
+import { degrees, pi } from "../../unit/angle";
+import { meters, radians, seconds } from "../../unit/base";
 import * as SafeMath from "../math";
 import { Measure } from "../measure";
 
@@ -12,6 +13,18 @@ describe("Math", () => {
         expect(SafeMath.divide(Measure.of(50, meters), Measure.of(10, seconds))).toEqual(Measure.of(5, mps));
     });
 
+    it("trig", () => {
+        const zeroRadians = Measure.of(0, radians);
+        const zero = Measure.dimensionless(0);
+        expect(SafeMath.cos(zeroRadians)).toEqual(Measure.dimensionless(1));
+        expect(SafeMath.sin(zeroRadians)).toEqual(zero);
+        expect(SafeMath.tan(zeroRadians)).toEqual(zero);
+        expect(SafeMath.acos(zero)).toEqual(Measure.of(0.5, pi));
+        expect(SafeMath.asin(zero)).toEqual(zeroRadians);
+        expect(SafeMath.atan(zero)).toEqual(zeroRadians);
+        expect(SafeMath.atan2(Measure.of(5, meters), Measure.of(5, meters))).toEqual(Measure.of(45, degrees));
+    });
+
     it("abs", () => {
         expect(SafeMath.abs(Measure.of(-10, mps))).toEqual(Measure.of(10, mps));
     });

src/measure/math.ts

@@ -1,18 +1,30 @@
 import { Exponent } from "../exponent/common";
+import { Dimensionless, Length, PlaneAngle } from "../quantity/quantities";
+import { radians } from "../unit/base";
 import { Measure } from "./measure";
 import { DivideUnits, ExponentiateUnit, MultiplyUnits, NthRootableUnit, NthRootUnit, Unit } from "./types";
 import { nthRootUnit } from "./units";
 
 export const abs = wrapUnary(Math.abs);
+export const acos = wrapInverseTrig(Math.acos);
+export const asin = wrapInverseTrig(Math.asin);
+export const atan = wrapInverseTrig(Math.atan);
 export const ceil = wrapUnary(Math.ceil);
+export const cos = wrapTrig(Math.cos);
 export const floor = wrapUnary(Math.floor);
 export const fround = wrapUnary(Math.fround);
 export const hypot = warpNary(Math.hypot);
 export const max = warpNary(Math.max);
 export const min = warpNary(Math.min);
 export const round = wrapUnary(Math.round);
+export const sin = wrapTrig(Math.sin);
+export const tan = wrapTrig(Math.tan);
 export const trunc = wrapUnary(Math.trunc);
 
+export function atan2(y: Length, x: Length): PlaneAngle {
+    return Measure.of(Math.atan2(y.value, x.value), radians);
+}
+
 export function pow<U extends Unit, Y extends Exponent>(x: Measure<U>, y: Y): Measure<ExponentiateUnit<U, Y>> {
     return x.toThe(y);
 }
@@ -61,6 +73,18 @@ function wrapUnary(f: (x: number) => number) {
     };
 }
 
+function wrapTrig(f: (x: number) => number) {
+    return (angle: PlaneAngle): Dimensionless => {
+        return Measure.dimensionless(f(angle.value));
+    };
+}
+
+function wrapInverseTrig(f: (x: number) => number) {
+    return (angle: Dimensionless): PlaneAngle => {
+        return Measure.of(f(angle.value), radians);
+    };
+}
+
 function warpNary(f: (...x: number[]) => number) {
     return <U extends Unit>(first: Measure<U>, ...rest: Array<Measure<U>>): Measure<U> => {
         return Measure.of(f(...values(first, ...rest)), first.normalized());