[FIXED] How to define an f(x) function from a list in python

Issue

I would appreciate help on this. I have a list of the form [-100,20,30,40,50].

I need to create a function of the form -100+20x+30x**2+40x**3+50x**5.

I understand that some kind of a for-loop is needed in order to make the transformation, such as:

for i in range(len(lst)):
    lambda x: sum(lst[i]*x**i)

output is as follows:

<function irr_newton.<locals>.<lambda> at 0x7fb98844ad30>

Solution

There numerous ways to do this. But if you want to use lambda, this is one way to do it.

coefs = [-100,20,30,40,50]
function = lambda x: sum([coef*x**i for i, coef in enumerate(coefs)])

Test:

function(2)

Output:

1180

Alternatively, you can go about it using a for loop:

def function(x):
    coefs = [-100,20,30,40,50]
    
    result = 0
    for i, num in enumerate(coefs):
        result += num*x**i
        
    return result

I thought of one more solution, where you use a recursive function.

coefs = [-100,20,30,40,50]
def function(x):
    if coefs == []:
        return 0
    
    result = coefs.pop(-1)*x**(len(coefs))
    
    return function(x) + result

Answered By - Emmanuel