已知 sqrt (2)约等于 1.414，要求不用数学库，求 sqrt (2)精确到小数点后 10 位

二分法：

package main

import "fmt"

func sqrt2() float64{
  low := 1.4
  high := 1.5
  var mid float64
  for high-low > 0.0000000001{
    mid = (low+high)/2
    if mid*mid>2 {
      high = mid
    }else {
      low = mid
    }
  }
  return mid
}

func main()  {
  fmt.Printf("%.10f",sqrt2())
}