1// Copyright 2018 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// Disabled for s390x because it uses assembly routines that are not
6// accurate for huge arguments.
7
8// +build !s390x
9
10package math_test
11
12import (
13	. "math"
14	"testing"
15)
16
17// Inputs to test trig_reduce
18var trigHuge = []float64{
19	1 << 120,
20	1 << 240,
21	1 << 480,
22	1234567891234567 << 180,
23	1234567891234567 << 300,
24	MaxFloat64,
25}
26
27// Results for trigHuge[i] calculated with https://github.com/robpike/ivy
28// using 4096 bits of working precision.   Values requiring less than
29// 102 decimal digits (1 << 120, 1 << 240, 1 << 480, 1234567891234567 << 180)
30// were confirmed via https://keisan.casio.com/
31var cosHuge = []float64{
32	-0.92587902285483787,
33	0.93601042593353793,
34	-0.28282777640193788,
35	-0.14616431394103619,
36	-0.79456058210671406,
37	-0.99998768942655994,
38}
39
40var sinHuge = []float64{
41	0.37782010936075202,
42	-0.35197227524865778,
43	0.95917070894368716,
44	0.98926032637023618,
45	-0.60718488235646949,
46	0.00496195478918406,
47}
48
49var tanHuge = []float64{
50	-0.40806638884180424,
51	-0.37603456702698076,
52	-3.39135965054779932,
53	-6.76813854009065030,
54	0.76417695016604922,
55	-0.00496201587444489,
56}
57
58// Check that trig values of huge angles return accurate results.
59// This confirms that argument reduction works for very large values
60// up to MaxFloat64.
61func TestHugeCos(t *testing.T) {
62	for i := 0; i < len(trigHuge); i++ {
63		f1 := cosHuge[i]
64		f2 := Cos(trigHuge[i])
65		if !close(f1, f2) {
66			t.Errorf("Cos(%g) = %g, want %g", trigHuge[i], f2, f1)
67		}
68	}
69}
70
71func TestHugeSin(t *testing.T) {
72	for i := 0; i < len(trigHuge); i++ {
73		f1 := sinHuge[i]
74		f2 := Sin(trigHuge[i])
75		if !close(f1, f2) {
76			t.Errorf("Sin(%g) = %g, want %g", trigHuge[i], f2, f1)
77		}
78	}
79}
80
81func TestHugeSinCos(t *testing.T) {
82	for i := 0; i < len(trigHuge); i++ {
83		f1, g1 := sinHuge[i], cosHuge[i]
84		f2, g2 := Sincos(trigHuge[i])
85		if !close(f1, f2) || !close(g1, g2) {
86			t.Errorf("Sincos(%g) = %g, %g, want %g, %g", trigHuge[i], f2, g2, f1, g1)
87		}
88	}
89}
90
91func TestHugeTan(t *testing.T) {
92	for i := 0; i < len(trigHuge); i++ {
93		f1 := tanHuge[i]
94		f2 := Tan(trigHuge[i])
95		if !close(f1, f2) {
96			t.Errorf("Tan(%g) = %g, want %g", trigHuge[i], f2, f1)
97		}
98	}
99}
100