Write a function to let user calculate value of a function at an abitrary point-CodePudding

Problem: Write a function to let the user calculate the value of a function f(x) at an arbitrary point x = a

Input: a
Output: value of the function f at x = a

Apply to calculate the value of f(x)= sqrt(x-2) at x=4.

My question: I don't know clearly the meaning of this problem. If we want to calculate the value of a function, we can assign a value we need and put it in a function without defining a function like this?

CodePudding user response：

Yes. You can use something like eval. You don't actually need to define a function in your code. Instead, you can put it in a string and pass it to eval.

Try something like this:

import math

a = int(input())
f = 'math.sqrt(x-2)'
x = a

print(eval(f))

You could change f to any function, or even read f from input as a string.

CodePudding user response：

You have a as input and f(a) as output, but the problem says define a function to apply f on a. So, instead of directly writing f(a) you write eval_func(a) that returns the same f(a).

import math 

def eval_func(a):
    x = a
    return math.sqrt(x-2)

Run with input 4:

eval_func(4)
1.4142135623730951