julenum/beta_test.jule at master · mertcandav/julenum · GitHub

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// Copyright 2025 mertcandav.
// Use of this source code is governed by a BSD 3-Clause
// license that can be found in the LICENSE file.

use "std/math"
use "std/testing"

struct betaTest {
	p:    f64
	q:    f64
	want: f64
}

let testsBeta: []betaTest = [
	{
		p: 1,
		q: 2,
		want: 0.5, // obtained from scipy.special.beta(1,2) (version=0.18.0)
	},
	{
		p: 10,
		q: 20,
		want: 4.9925087406346778e-09, // obtained from scipy.special.beta(10,20) (version=0.18.0)
	},
	{
		p: +0,
		q: 10,
		want: math::Inf(+1),
	},
	{
		p: -0,
		q: 10,
		want: math::Inf(+1),
	},
	{
		p: 0,
		q: 0,
		want: math::NaN(),
	},
	{
		p: 0,
		q: math::Inf(-1),
		want: math::NaN(),
	},
	{
		p: 10,
		q: math::Inf(-1),
		want: math::NaN(),
	},
	{
		p: 0,
		q: math::Inf(+1),
		want: math::NaN(),
	},
	{
		p: 10,
		q: math::Inf(+1),
		want: math::NaN(),
	},
	{
		p: math::NaN(),
		q: 10,
		want: math::NaN(),
	},
	{
		p: math::NaN(),
		q: 0,
		want: math::NaN(),
	},
	{
		p: -1,
		q: 0,
		want: math::NaN(),
	},
	{
		p: -1,
		q: +1,
		want: math::NaN(),
	},
]

#test
fn testBeta(t: &testing::T) {
	for i, test in testsBeta {
		v := Beta(test.p, test.q)
		if !(Tolerance(v, test.want, 1e-12) ||
			(math::IsNaN(test.want) && math::IsNaN(v))) {
			t.Errorf("test #{}: Beta({}, {})={}. want={}",
				i, test.p, test.q, v, test.want)
		}

		u := Beta(test.q, test.p)
		if !(Tolerance(u, test.want, 1e-12) ||
			(math::IsNaN(test.want) && math::IsNaN(u))) {
			t.Errorf("test #{}: Beta({}, {})={}. want={}",
				i, test.q, test.p, u, test.want)
		}

		if math::IsInf(v, +1) || math::IsNaN(v) {
			continue
		}

		vv := Beta(test.p, test.q+1)
		uu := Beta(test.p+1, test.q)
		if !Tolerance(v, vv+uu, 1e-12) {
			t.Errorf("test #{}: Beta(p,q) != Beta(p,q+1)+Beta(p+1,q)")
		}

		vbeta2 := beta2(test.p, test.q)
		if !Tolerance(v, vbeta2, 1e-12) {
			t.Errorf("test #{}: Beta(p,q) != Beta2(p,q)")
		}
	}
}

fn beta2(x: f64, y: f64): f64 {
	ret math::Gamma(x) * math::Gamma(y) / math::Gamma(x+y)
}

#test
fn testLbeta(t: &testing::T) {
	for i, test in testsBeta {
		want := math::Log(test.want)
		v := Lbeta(test.p, test.q)
		if !(Tolerance(v, want, 1e-15) ||
			(math::IsNaN(want) && math::IsNaN(v))) {
			t.Errorf("test #{}: Lbeta({}, {})={}. want={}",
				i, test.p, test.q, v, want)
		}

		u := Lbeta(test.q, test.p)
		if !(Tolerance(u, want, 1e-15) ||
			(math::IsNaN(want) && math::IsNaN(u))) {
			t.Errorf("test #{}: Lbeta({}, {})={}. want={}",
				i, test.q, test.p, u, want)
		}

		if math::IsInf(v, +1) || math::IsNaN(v) {
			continue
		}

		vbeta2 := math::Log(beta2(test.p, test.q))
		if !Tolerance(v, vbeta2, 1e-15) {
			t.Errorf("test #{}: Lbeta(p,q) != Log(Beta2(p,q))")
		}
	}
}