math: Applied remarks

Author: essobedo

lib/math/math.go

@@ -1,4 +1,9 @@
-package math
+// Copyright 2021 The Bazel Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package math provides basic constants and mathematical functions.
+package math // import "go.starlark.net/lib/math"
 
 import (
 	"math"
@@ -7,15 +12,22 @@ import (
 	"go.starlark.net/starlarkstruct"
 )
 
-const tau = math.Pi * 2
-const oneRad = tau / 360
+const (
+	tau    = math.Pi * 2
+	oneRad = tau / 360
+)
 
-// Module math is a Starlark module of math-related functions.
+var (
+	toDeg = func(x float64) float64 { return x / oneRad }
+	toRad = func(x float64) float64 { return x * oneRad }
+)
+
+// Module math is a Starlark module of math-related functions and constants.
 var Module = &starlarkstruct.Module{
 	Name: "math",
 	Members: starlark.StringDict{
+		"abs":   starlark.NewBuiltin("abs", abs),
 		"ceil":  starlark.NewBuiltin("ceil", ceil),
-		"fabs":  starlark.NewBuiltin("fabs", fabs),
 		"floor": starlark.NewBuiltin("floor", floor),
 		"round": starlark.NewBuiltin("round", round),
 
@@ -42,59 +54,145 @@ var Module = &starlarkstruct.Module{
 		"tanh":  starlark.NewBuiltin("tanh", tanh),
 
 		"e":   starlark.Float(math.E),
-		"pi":  starlark.Float(math.Pi),
-		"tau": starlark.Float(tau),
 		"phi": starlark.Float(math.Phi),
-		"inf": starlark.Float(math.Inf(1)),
-		"nan": starlark.Float(math.NaN()),
+		"pi":  starlark.Float(math.Pi),
 	},
 }
 
-// floatFunc unpacks a starlark function call, calls a passed in float64 function
-// and returns the result as a starlark value
-func floatFunc(name string, args starlark.Tuple, kwargs []starlark.Tuple, fn func(float64) float64) (starlark.Value, error) {
-	var x starlark.Float
+// oneArgFunc unpacks a starlark function call with one argument, calls a passed in function taking one float64 as argument
+// and returns the result as a starlark value.
+func oneArgFunc(name string, args starlark.Tuple, kwargs []starlark.Tuple, fn func(float64) float64) (starlark.Value, error) {
+	var x float64
 	if err := starlark.UnpackPositionalArgs(name, args, kwargs, 1, &x); err != nil {
-		return nil, err
+		var i int64
+		if starlark.UnpackPositionalArgs(name, args, kwargs, 1, &i) != nil {
+			return nil, err
+		}
+		x = float64(i)
 	}
-	return starlark.Float(fn(float64(x))), nil
+	return starlark.Float(fn(x)), nil
 }
 
-// floatFunc2 is a 2-argument float func
-func floatFunc2(name string, args starlark.Tuple, kwargs []starlark.Tuple, fn func(float64, float64) float64) (starlark.Value, error) {
-	var x, y starlark.Float
+// twoArgFunc unpacks a starlark function call with two arguments, calls a passed in function taking two float64 as argument
+// and returns the result as a starlark value.
+func twoArgFunc(name string, args starlark.Tuple, kwargs []starlark.Tuple, fn func(float64, float64) float64) (starlark.Value, error) {
+	var x, y float64
 	if err := starlark.UnpackPositionalArgs(name, args, kwargs, 2, &x, &y); err != nil {
 		return nil, err
 	}
-	return starlark.Float(fn(float64(x), float64(y))), nil
+	return starlark.Float(fn(x, y)), nil
 }
 
-// Return the floor of x, the largest integer less than or equal to x.
+// floor(x) - Return the floor of x, the largest integer less than or equal to x.
 func floor(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
-	return floatFunc("floor", args, kwargs, math.Floor)
+	return oneArgFunc("floor", args, kwargs, math.Floor)
 }
 
-// Return the ceiling of x, the smallest integer greater than or equal to x
+// ceil(x) - Return the ceiling of x, the smallest integer greater than or equal to x.
 func ceil(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
-	return floatFunc("ceil", args, kwargs, math.Ceil)
+	return oneArgFunc("ceil", args, kwargs, math.Ceil)
 }
 
-// Return the absolute value of x
-func fabs(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
-	return floatFunc("fabs", args, kwargs, math.Abs)
+// abs(x) - Return the absolute value of x.
+func abs(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("abs", args, kwargs, math.Abs)
 }
 
-// Round returns the nearest integer, rounding half away from zero.
+// round(x) - Round returns the nearest integer, rounding half away from zero.
 func round(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
-	return floatFunc("fabs", args, kwargs, math.Round)
+	return oneArgFunc("round", args, kwargs, math.Round)
 }
 
-// Return e raised to the power x, where e = 2.718281… is the base of natural logarithms.
+// exp(x) - Return e raised to the power x, where e = 2.718281… is the base of natural logarithms.
 func exp(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
-	return floatFunc("exp", args, kwargs, math.Exp)
+	return oneArgFunc("exp", args, kwargs, math.Exp)
 }
 
-// Return the square root of x
+// sqrt(x) - Return the square root of x.
 func sqrt(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
-	return floatFunc("sqrt", args, kwargs, math.Sqrt)
+	return oneArgFunc("sqrt", args, kwargs, math.Sqrt)
+}
+
+// acos(x) - Return the arc cosine of x, in radians.
+func acos(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("acos", args, kwargs, math.Acos)
+}
+
+// asin(x) - Return the arc sine of x, in radians.
+func asin(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("asin", args, kwargs, math.Asin)
+}
+
+// atan(x) - Return the arc tangent of x, in radians.
+func atan(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("atan", args, kwargs, math.Atan)
+}
+
+// atan2(y, x) - Return atan(y / x), in radians.
+// The result is between -pi and pi.
+// The vector in the plane from the origin to point (x, y) makes this angle with the positive X axis.
+// The point of atan2() is that the signs of both inputs are known to it, so it can compute the correct quadrant for the angle.
+// For example, atan(1) and atan2(1, 1) are both pi/4, but atan2(-1, -1) is -3*pi/4.
+func atan2(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return twoArgFunc("atan2", args, kwargs, math.Atan2)
+}
+
+// cos(x) - Return the cosine of x, in radians.
+func cos(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("cos", args, kwargs, math.Cos)
+}
+
+// hypot(x, y) - Return the Euclidean norm, sqrt(x*x + y*y). This is the length of the vector from the origin to point (x, y).
+func hypot(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return twoArgFunc("hypot", args, kwargs, math.Hypot)
+}
+
+// sin(x) - Return the sine of x, in radians.
+func sin(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("sin", args, kwargs, math.Sin)
+}
+
+// tan(x) - Return the tangent of x, in radians.
+func tan(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("tan", args, kwargs, math.Tan)
+}
+
+// degrees(x) - Convert angle x from radians to degrees.
+func degrees(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("degrees", args, kwargs, toDeg)
+}
+
+// radians(x) - Convert angle x from degrees to radians.
+func radians(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("radians", args, kwargs, toRad)
+}
+
+// acosh(x) - Return the inverse hyperbolic cosine of x.
+func acosh(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("acosh", args, kwargs, math.Acosh)
+}
+
+// asinh(x) - Return the inverse hyperbolic sine of x.
+func asinh(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("asinh", args, kwargs, math.Asinh)
+}
+
+// atanh(x) - Return the inverse hyperbolic tangent of x.
+func atanh(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("atanh", args, kwargs, math.Atanh)
+}
+
+// cosh(x) - Return the hyperbolic cosine of x.
+func cosh(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("cosh", args, kwargs, math.Cosh)
+}
+
+// sinh(x) - Return the hyperbolic sine of x.
+func sinh(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("sinh", args, kwargs, math.Sinh)
+}
+
+// tanh(x) - Return the hyperbolic tangent of x.
+func tanh(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	return oneArgFunc("tanh", args, kwargs, math.Tanh)
 }