#🔒 Help needed with Newtons Method code

14 messages · Page 1 of 1 (latest)

austere atlas
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Hi! So I'm not exactly an expert with Python, nor am I with Calculus, yet I tried to code a program that would work to solve Newtons Method. Nevertheless, even if the code seems alright, the answers that I am getting are not even close to the correct, checked answer. I believe it might be due to the fact that the program isn't taking into account the iterations and the change of the value of x when iterating. I was wondering if someone could please help me out with this? I really cannot see what the problem is and how to fix it. Thank you in advance!:

def newtonsmethod(ftn, fprime, x0, n):
    
    def f(x):
        return eval(ftn)
    
    def df(x):
        return eval(fprime)

    x=x0  

    for iterations in range(1,n+1):
        x = x - (f(x)/df(x))
    return x

n=100

ans=newtonsmethod("x**-2", "-2*x**-3", 1.4, 100)

print (f"The root was found to be at {ans} after {n} iterations")```
bronze thunderBOT
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@austere atlas

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hushed falcon
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x^(-2) does not have any roots.

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Using Newton's method on 1.4 would cause the number to grow to a huge positive, if I'm not wrong.

austere atlas
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I thought it would be in fact a coding issue as its not an issue with the formulas itself, but with the iteration thing. maybe because I used a "for" instead of a "while" loop, although I don't really understand how I would do that :')?

hushed falcon
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As I've told you, it's not an issue with the formula. It's that you used y = 1/x² which has no roots.

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Try using y = 1/x² - 3 instead

austere atlas
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that makes sense lol

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thank you so much!!!

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: )

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!close

bronze thunderBOT
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