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Source file src/runtime/sqrt_test.go

Documentation: runtime

  // Copyright 2015 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.
  
  // A copy of Sqrt tests from the math package to test the
  // purely integer arithmetic implementation in sqrt.go.
  
  package runtime_test
  
  import (
  	"math"
  	"runtime"
  	"testing"
  )
  
  func SqrtRT(x float64) float64 {
  	return math.Float64frombits(runtime.Sqrt(math.Float64bits(x)))
  }
  
  func TestSqrt(t *testing.T) {
  	for i := 0; i < len(vf); i++ {
  		a := math.Abs(vf[i])
  		if f := SqrtRT(a); sqrt[i] != f {
  			t.Errorf("Sqrt(%g) = %g, want %g", a, f, sqrt[i])
  		}
  	}
  	for i := 0; i < len(vfsqrtSC); i++ {
  		if f := SqrtRT(vfsqrtSC[i]); !alike(sqrtSC[i], f) {
  			t.Errorf("Sqrt(%g) = %g, want %g", vfsqrtSC[i], f, sqrtSC[i])
  		}
  	}
  }
  
  func alike(a, b float64) bool {
  	switch {
  	case math.IsNaN(a) && math.IsNaN(b):
  		return true
  	case a == b:
  		return math.Signbit(a) == math.Signbit(b)
  	}
  	return false
  }
  
  var vf = []float64{
  	4.9790119248836735e+00,
  	7.7388724745781045e+00,
  	-2.7688005719200159e-01,
  	-5.0106036182710749e+00,
  	9.6362937071984173e+00,
  	2.9263772392439646e+00,
  	5.2290834314593066e+00,
  	2.7279399104360102e+00,
  	1.8253080916808550e+00,
  	-8.6859247685756013e+00,
  }
  
  var sqrt = []float64{
  	2.2313699659365484748756904e+00,
  	2.7818829009464263511285458e+00,
  	5.2619393496314796848143251e-01,
  	2.2384377628763938724244104e+00,
  	3.1042380236055381099288487e+00,
  	1.7106657298385224403917771e+00,
  	2.286718922705479046148059e+00,
  	1.6516476350711159636222979e+00,
  	1.3510396336454586262419247e+00,
  	2.9471892997524949215723329e+00,
  }
  
  var vfsqrtSC = []float64{
  	math.Inf(-1),
  	-math.Pi,
  	math.Copysign(0, -1),
  	0,
  	math.Inf(1),
  	math.NaN(),
  	math.Float64frombits(2),
  }
  var sqrtSC = []float64{
  	math.NaN(),
  	math.NaN(),
  	math.Copysign(0, -1),
  	0,
  	math.Inf(1),
  	math.NaN(),
  	3.1434555694052576e-162,
  }
  

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