dousu8767
2018-11-03 09:06
浏览 98
已采纳

究竟math.Exp有什么作用?

Sorry, but I am not able to understand what exactly math.Exp is doing in following code block:

package main

import (
    "fmt"
    "math"
)

func main() {
    for x := 0; x < 8; x++ {
        fmt.Printf("x = %f ex = %8.3f
", float64(x), math.Exp(float64(x)))
    }
}

The output of the above program is:

x = 0.000000 ex =    1.000
x = 1.000000 ex =    2.718
x = 2.000000 ex =    7.389
x = 3.000000 ex =   20.086
x = 4.000000 ex =   54.598
x = 5.000000 ex =  148.413
x = 6.000000 ex =  403.429
x = 7.000000 ex = 1096.633

And, I am not able to understand what exactly is math.Exp function is doing internally and converting float64(x) to respective values as in the output. I have read the go's official documentation, which says as below:

Exp returns e**x, the base-e exponential of x.

Reading which I am not very clear of the purpose and mechanism of math.Exp function.

I am actually interested in what binary/mathematical operation is going under the hood.

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1条回答 默认 最新

  • dpnfxk251524 2018-11-03 09:27
    已采纳

    It returns the value of e^x (also expressed as e**x or simply exp(x)).

    That function is based on the number e=2.71828... [1], which is defined (among other definitions) as:

    Lim (1+1/n)^n when n tends to infinity
    

    Particularly, the function e^x has many properties that make it special, but the "most" important is the fact that the function itself is equal to its derivative, i.e.:

    Let f(x)=e^x, then f'(x)=e^x

    This translates to the fact that the value of the slope in one point is equal to the value of the function in that point.

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