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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