# Source file src/math/huge_test.go

```     1  // Copyright 2018 The Go Authors. All rights reserved.
2  // Use of this source code is governed by a BSD-style
4
5  package math_test
6
7  import (
8  	. "math"
9  	"testing"
10  )
11
12  // Inputs to test trig_reduce
13  var 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/
30  var 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
43  var 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
56  var 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.
72  func 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
86  func 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
100  func 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
114  func 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
```

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