Btukfyl

import math



def g(x):

    return x**2+3



def Integrate(f, a , b, n):

    h=(b-a)/n

    result=0

    for k in range(n):

        x=k*h+h/2

        result+=f(x)*h

    return result



F=input("f:")

A=float(input("a:"))

B=float(input("b:"))

N=int(input("n:"))

print(Integrate(F, A, B, N))

Whenever i try to run this code, it reads F to be a string and gives an error when called in integrate(f, a, b, n). I found that there is no way in python to define F as a function, but calling a function in another function is definitely possible. Then how can i still pull this way of using an input to specify what function to use off?

error:

 line 14, in Integrate

    result+=f(x)*h

TypeError: 'str' object is not callable

You can input a function on the console by using a lambda (as a string), and use eval to convert the string to an actual function object. Your code would look like this:

F = eval(input("f:"))

On the console, if you want to integrate the function f(x) = 2 * x + 1, you'd input:

lambda x: 2 * x + 1

as a string. However, note that eval will execute (as Python code) whatever you input on the console, and this could be a security concern depending on how your program is used.

I don't know if you want to use function from math module, but if yes then you can obtain method from module by string like this:

function_to_call = getattr(math, f)

result += function_to_call(x) * h

When doing this you should surround with try except block to check if given function name exit in math module.