数的三次方根-golang

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数的三次方根-golang

package main

import (
    "fmt"
    "math"
)

func search(x float64) float64 {
    const eps = 1e-8
    sign := 1
    // 负数
    if x < 0 {
        x = math.Abs(x)
        sign = -1
    }

    l, r := 0.0, math.Max(1.0, x)

    for math.Abs(l - r) > eps {
        mid := (l + r) / 2
        if (math.Pow(mid, 3) - x) > eps {
            r = mid
            continue
        }
        l = mid
    }

    return float64(sign) * l
}

func main() {
    var num float64
    fmt.Scanf("%f", &num)

    fmt.Printf("%.6f\n", search(num))
}