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
5package math_test
6
7import (
8	. "math"
9	"testing"
10)
11
12// Inputs to test trig_reduce
13var trigHuge = []float64{
14	1 << 28,
15	1 << 29,
16	1 << 30,
17	1 << 35,
18	1 << 120,
19	1 << 240,
20	1 << 480,
21	1234567891234567 << 180,
22	1234567891234567 << 300,
23	MaxFloat64,
24}
25
26// Results for trigHuge[i] calculated with https://github.com/robpike/ivy
27// using 4096 bits of working precision.   Values requiring less than
28// 102 decimal digits (1 << 120, 1 << 240, 1 << 480, 1234567891234567 << 180)
29// were confirmed via https://keisan.casio.com/
30var cosHuge = []float64{
31	-0.16556897949057876,
32	-0.94517382606089662,
33	0.78670712294118812,
34	-0.76466301249635305,
35	-0.92587902285483787,
36	0.93601042593353793,
37	-0.28282777640193788,
38	-0.14616431394103619,
39	-0.79456058210671406,
40	-0.99998768942655994,
41}
42
43var sinHuge = []float64{
44	-0.98619821183697566,
45	0.32656766301856334,
46	-0.61732641504604217,
47	-0.64443035102329113,
48	0.37782010936075202,
49	-0.35197227524865778,
50	0.95917070894368716,
51	0.98926032637023618,
52	-0.60718488235646949,
53	0.00496195478918406,
54}
55
56var tanHuge = []float64{
57	5.95641897939639421,
58	-0.34551069233430392,
59	-0.78469661331920043,
60	0.84276385870875983,
61	-0.40806638884180424,
62	-0.37603456702698076,
63	-3.39135965054779932,
64	-6.76813854009065030,
65	0.76417695016604922,
66	-0.00496201587444489,
67}
68
69// Check that trig values of huge angles return accurate results.
70// This confirms that argument reduction works for very large values
71// up to MaxFloat64.
72func TestHugeCos(t *testing.T) {
73	for i := 0; i < len(trigHuge); i++ {
74		f1 := cosHuge[i]
75		f2 := Cos(trigHuge[i])
76		if !close(f1, f2) {
77			t.Errorf("Cos(%g) = %g, want %g", trigHuge[i], f2, f1)
78		}
79		f3 := Cos(-trigHuge[i])
80		if !close(f1, f3) {
81			t.Errorf("Cos(%g) = %g, want %g", -trigHuge[i], f3, f1)
82		}
83	}
84}
85
86func TestHugeSin(t *testing.T) {
87	for i := 0; i < len(trigHuge); i++ {
88		f1 := sinHuge[i]
89		f2 := Sin(trigHuge[i])
90		if !close(f1, f2) {
91			t.Errorf("Sin(%g) = %g, want %g", trigHuge[i], f2, f1)
92		}
93		f3 := Sin(-trigHuge[i])
94		if !close(-f1, f3) {
95			t.Errorf("Sin(%g) = %g, want %g", -trigHuge[i], f3, -f1)
96		}
97	}
98}
99
100func TestHugeSinCos(t *testing.T) {
101	for i := 0; i < len(trigHuge); i++ {
102		f1, g1 := sinHuge[i], cosHuge[i]
103		f2, g2 := Sincos(trigHuge[i])
104		if !close(f1, f2) || !close(g1, g2) {
105			t.Errorf("Sincos(%g) = %g, %g, want %g, %g", trigHuge[i], f2, g2, f1, g1)
106		}
107		f3, g3 := Sincos(-trigHuge[i])
108		if !close(-f1, f3) || !close(g1, g3) {
109			t.Errorf("Sincos(%g) = %g, %g, want %g, %g", -trigHuge[i], f3, g3, -f1, g1)
110		}
111	}
112}
113
114func TestHugeTan(t *testing.T) {
115	for i := 0; i < len(trigHuge); i++ {
116		f1 := tanHuge[i]
117		f2 := Tan(trigHuge[i])
118		if !close(f1, f2) {
119			t.Errorf("Tan(%g) = %g, want %g", trigHuge[i], f2, f1)
120		}
121		f3 := Tan(-trigHuge[i])
122		if !close(-f1, f3) {
123			t.Errorf("Tan(%g) = %g, want %g", -trigHuge[i], f3, -f1)
124		}
125	}
126}
127