59 lines
1.5 KiB
Go
59 lines
1.5 KiB
Go
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/*
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* @Author : huangzj
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* @Time : 2020/12/30 15:11
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* @Description：
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*/
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package go_cmp
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import (
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"fmt"
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"github.com/google/go-cmp/cmp"
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"github.com/google/go-cmp/cmp/cmpopts"
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"math"
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"testing"
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)
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type FloatPair struct {
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X float64
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Y float64
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}
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func TestBasicFloat(t *testing.T) {
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//特殊的浮点数NaN（Not a Number），它与任何浮点数都不等，包括它自己
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p1 := FloatPair{X: math.NaN()}
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p2 := FloatPair{X: math.NaN()}
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fmt.Println("p1 equals p2?", cmp.Equal(p1, p2))
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//受限于变量的存储空间，就会存在误差
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f1 := 0.1
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f2 := 0.2
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f3 := 0.3
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p3 := FloatPair{X: f1 + f2}
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p4 := FloatPair{X: f3}
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fmt.Println("p3 equals p4?", cmp.Equal(p3, p4))
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//Go 语言中这些字面量的运算直接是在编译器完成的，所以同样的值虽然受限于变量的存储空间，但是结果是一样的.
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p5 := FloatPair{X: 0.1 + 0.2}
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p6 := FloatPair{X: 0.3}
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fmt.Println("p5 equals p6?", cmp.Equal(p5, p6))
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}
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//通过equal方法测试NaN返回结果一致
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func TestNanEqual(t *testing.T) {
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p1 := FloatPair{X: math.NaN()}
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p2 := FloatPair{X: math.NaN()}
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fmt.Println("p1 equals p2?", cmp.Equal(p1, p2, cmpopts.EquateNaNs()))
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}
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//测试误差在一定的范围内 具体表示是：|x-y| ≤ max(fraction*min(|x|, |y|), margin)
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func TestCountError(t *testing.T) {
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f1 := 0.1
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f2 := 0.2
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f3 := 0.3
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p3 := FloatPair{X: f1 + f2}
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p4 := FloatPair{X: f3}
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fmt.Println(fmt.Sprintf("实际存储的值分别是：\n %v \n %v", p3.X, p4.X))
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fmt.Println("p3 equals p4?", cmp.Equal(p3, p4, cmpopts.EquateApprox(0.1, 0.001)))
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}
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