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# Source file src/math/huge_test.go

## Documentation: math

```     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  //go:build !s390x
9  // +build !s390x
10
11  package math_test
12
13  import (
14  	. "math"
15  	"testing"
16  )
17
18  // Inputs to test trig_reduce
19  var trigHuge = []float64{
20  	1 << 28,
21  	1 << 29,
22  	1 << 30,
23  	1 << 35,
24  	1 << 120,
25  	1 << 240,
26  	1 << 480,
27  	1234567891234567 << 180,
28  	1234567891234567 << 300,
29  	MaxFloat64,
30  }
31
32  // Results for trigHuge[i] calculated with https://github.com/robpike/ivy
33  // using 4096 bits of working precision.   Values requiring less than
34  // 102 decimal digits (1 << 120, 1 << 240, 1 << 480, 1234567891234567 << 180)
35  // were confirmed via https://keisan.casio.com/
36  var cosHuge = []float64{
37  	-0.16556897949057876,
38  	-0.94517382606089662,
39  	0.78670712294118812,
40  	-0.76466301249635305,
41  	-0.92587902285483787,
42  	0.93601042593353793,
43  	-0.28282777640193788,
44  	-0.14616431394103619,
45  	-0.79456058210671406,
46  	-0.99998768942655994,
47  }
48
49  var sinHuge = []float64{
50  	-0.98619821183697566,
51  	0.32656766301856334,
52  	-0.61732641504604217,
53  	-0.64443035102329113,
54  	0.37782010936075202,
55  	-0.35197227524865778,
56  	0.95917070894368716,
57  	0.98926032637023618,
58  	-0.60718488235646949,
59  	0.00496195478918406,
60  }
61
62  var tanHuge = []float64{
63  	5.95641897939639421,
64  	-0.34551069233430392,
65  	-0.78469661331920043,
66  	0.84276385870875983,
67  	-0.40806638884180424,
68  	-0.37603456702698076,
69  	-3.39135965054779932,
70  	-6.76813854009065030,
71  	0.76417695016604922,
72  	-0.00496201587444489,
73  }
74
75  // Check that trig values of huge angles return accurate results.
76  // This confirms that argument reduction works for very large values
77  // up to MaxFloat64.
78  func TestHugeCos(t *testing.T) {
79  	for i := 0; i < len(trigHuge); i++ {
80  		f1 := cosHuge[i]
81  		f2 := Cos(trigHuge[i])
82  		if !close(f1, f2) {
83  			t.Errorf("Cos(%g) = %g, want %g", trigHuge[i], f2, f1)
84  		}
85  	}
86  }
87
88  func TestHugeSin(t *testing.T) {
89  	for i := 0; i < len(trigHuge); i++ {
90  		f1 := sinHuge[i]
91  		f2 := Sin(trigHuge[i])
92  		if !close(f1, f2) {
93  			t.Errorf("Sin(%g) = %g, want %g", trigHuge[i], f2, f1)
94  		}
95  	}
96  }
97
98  func TestHugeSinCos(t *testing.T) {
99  	for i := 0; i < len(trigHuge); i++ {
100  		f1, g1 := sinHuge[i], cosHuge[i]
101  		f2, g2 := Sincos(trigHuge[i])
102  		if !close(f1, f2) || !close(g1, g2) {
103  			t.Errorf("Sincos(%g) = %g, %g, want %g, %g", trigHuge[i], f2, g2, f1, g1)
104  		}
105  	}
106  }
107
108  func TestHugeTan(t *testing.T) {
109  	for i := 0; i < len(trigHuge); i++ {
110  		f1 := tanHuge[i]
111  		f2 := Tan(trigHuge[i])
112  		if !close(f1, f2) {
113  			t.Errorf("Tan(%g) = %g, want %g", trigHuge[i], f2, f1)
114  		}
115  	}
116  }
117
```

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