github.com/c12o16h1/go/src@v0.0.0-20200114212001-5a151c0f00ed/math/huge_test.go (about)

     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  
    10  package math_test
    11  
    12  import (
    13  	. "math"
    14  	"testing"
    15  )
    16  
    17  // Inputs to test trig_reduce
    18  var 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/
    31  var cosHuge = []float64{
    32  	-0.92587902285483787,
    33  	0.93601042593353793,
    34  	-0.28282777640193788,
    35  	-0.14616431394103619,
    36  	-0.79456058210671406,
    37  	-0.99998768942655994,
    38  }
    39  
    40  var sinHuge = []float64{
    41  	0.37782010936075202,
    42  	-0.35197227524865778,
    43  	0.95917070894368716,
    44  	0.98926032637023618,
    45  	-0.60718488235646949,
    46  	0.00496195478918406,
    47  }
    48  
    49  var 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.
    61  func 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  
    71  func 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  
    81  func 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  
    91  func 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  }