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Source file src/runtime/sqrt_test.go

Documentation: runtime

     1  // Copyright 2015 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  // A copy of Sqrt tests from the math package to test the
     6  // purely integer arithmetic implementation in sqrt.go.
     7  
     8  package runtime_test
     9  
    10  import (
    11  	"math"
    12  	"runtime"
    13  	"testing"
    14  )
    15  
    16  func SqrtRT(x float64) float64 {
    17  	return math.Float64frombits(runtime.Sqrt(math.Float64bits(x)))
    18  }
    19  
    20  func TestSqrt(t *testing.T) {
    21  	for i := 0; i < len(vf); i++ {
    22  		a := math.Abs(vf[i])
    23  		if f := SqrtRT(a); sqrt[i] != f {
    24  			t.Errorf("Sqrt(%g) = %g, want %g", a, f, sqrt[i])
    25  		}
    26  	}
    27  	for i := 0; i < len(vfsqrtSC); i++ {
    28  		if f := SqrtRT(vfsqrtSC[i]); !alike(sqrtSC[i], f) {
    29  			t.Errorf("Sqrt(%g) = %g, want %g", vfsqrtSC[i], f, sqrtSC[i])
    30  		}
    31  	}
    32  }
    33  
    34  func alike(a, b float64) bool {
    35  	switch {
    36  	case math.IsNaN(a) && math.IsNaN(b):
    37  		return true
    38  	case a == b:
    39  		return math.Signbit(a) == math.Signbit(b)
    40  	}
    41  	return false
    42  }
    43  
    44  var vf = []float64{
    45  	4.9790119248836735e+00,
    46  	7.7388724745781045e+00,
    47  	-2.7688005719200159e-01,
    48  	-5.0106036182710749e+00,
    49  	9.6362937071984173e+00,
    50  	2.9263772392439646e+00,
    51  	5.2290834314593066e+00,
    52  	2.7279399104360102e+00,
    53  	1.8253080916808550e+00,
    54  	-8.6859247685756013e+00,
    55  }
    56  
    57  var sqrt = []float64{
    58  	2.2313699659365484748756904e+00,
    59  	2.7818829009464263511285458e+00,
    60  	5.2619393496314796848143251e-01,
    61  	2.2384377628763938724244104e+00,
    62  	3.1042380236055381099288487e+00,
    63  	1.7106657298385224403917771e+00,
    64  	2.286718922705479046148059e+00,
    65  	1.6516476350711159636222979e+00,
    66  	1.3510396336454586262419247e+00,
    67  	2.9471892997524949215723329e+00,
    68  }
    69  
    70  var vfsqrtSC = []float64{
    71  	math.Inf(-1),
    72  	-math.Pi,
    73  	math.Copysign(0, -1),
    74  	0,
    75  	math.Inf(1),
    76  	math.NaN(),
    77  	math.Float64frombits(2),
    78  }
    79  var sqrtSC = []float64{
    80  	math.NaN(),
    81  	math.NaN(),
    82  	math.Copysign(0, -1),
    83  	0,
    84  	math.Inf(1),
    85  	math.NaN(),
    86  	3.1434555694052576e-162,
    87  }
    88  

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