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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