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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package math_test
import (
. "math"
"testing"
)
// Inputs to test trig_reduce
var trigHuge = []float64{
1 << 28,
1 << 29,
1 << 30,
1 << 35,
1 << 120,
1 << 240,
1 << 480,
1234567891234567 << 180,
1234567891234567 << 300,
MaxFloat64,
}
// Results for trigHuge[i] calculated with https://github.com/robpike/ivy
// using 4096 bits of working precision. Values requiring less than
// 102 decimal digits (1 << 120, 1 << 240, 1 << 480, 1234567891234567 << 180)
// were confirmed via https://keisan.casio.com/
var cosHuge = []float64{
-0.16556897949057876,
-0.94517382606089662,
0.78670712294118812,
-0.76466301249635305,
-0.92587902285483787,
0.93601042593353793,
-0.28282777640193788,
-0.14616431394103619,
-0.79456058210671406,
-0.99998768942655994,
}
var sinHuge = []float64{
-0.98619821183697566,
0.32656766301856334,
-0.61732641504604217,
-0.64443035102329113,
0.37782010936075202,
-0.35197227524865778,
0.95917070894368716,
0.98926032637023618,
-0.60718488235646949,
0.00496195478918406,
}
var tanHuge = []float64{
5.95641897939639421,
-0.34551069233430392,
-0.78469661331920043,
0.84276385870875983,
-0.40806638884180424,
-0.37603456702698076,
-3.39135965054779932,
-6.76813854009065030,
0.76417695016604922,
-0.00496201587444489,
}
// Check that trig values of huge angles return accurate results.
// This confirms that argument reduction works for very large values
// up to MaxFloat64.
func TestHugeCos(t *testing.T) {
for i := 0; i < len(trigHuge); i++ {
f1 := cosHuge[i]
f2 := Cos(trigHuge[i])
if !close(f1, f2) {
t.Errorf("Cos(%g) = %g, want %g", trigHuge[i], f2, f1)
}
f3 := Cos(-trigHuge[i])
if !close(f1, f3) {
t.Errorf("Cos(%g) = %g, want %g", -trigHuge[i], f3, f1)
}
}
}
func TestHugeSin(t *testing.T) {
for i := 0; i < len(trigHuge); i++ {
f1 := sinHuge[i]
f2 := Sin(trigHuge[i])
if !close(f1, f2) {
t.Errorf("Sin(%g) = %g, want %g", trigHuge[i], f2, f1)
}
f3 := Sin(-trigHuge[i])
if !close(-f1, f3) {
t.Errorf("Sin(%g) = %g, want %g", -trigHuge[i], f3, -f1)
}
}
}
func TestHugeSinCos(t *testing.T) {
for i := 0; i < len(trigHuge); i++ {
f1, g1 := sinHuge[i], cosHuge[i]
f2, g2 := Sincos(trigHuge[i])
if !close(f1, f2) || !close(g1, g2) {
t.Errorf("Sincos(%g) = %g, %g, want %g, %g", trigHuge[i], f2, g2, f1, g1)
}
f3, g3 := Sincos(-trigHuge[i])
if !close(-f1, f3) || !close(g1, g3) {
t.Errorf("Sincos(%g) = %g, %g, want %g, %g", -trigHuge[i], f3, g3, -f1, g1)
}
}
}
func TestHugeTan(t *testing.T) {
for i := 0; i < len(trigHuge); i++ {
f1 := tanHuge[i]
f2 := Tan(trigHuge[i])
if !close(f1, f2) {
t.Errorf("Tan(%g) = %g, want %g", trigHuge[i], f2, f1)
}
f3 := Tan(-trigHuge[i])
if !close(-f1, f3) {
t.Errorf("Tan(%g) = %g, want %g", -trigHuge[i], f3, -f1)
}
}
}