segmentation fault in pi calculation (python)

Question

def pi(times):
    seq = []
    counter = 0
    for x in range(times):
        counter += 2
        seq.append(\"((%f**2)/(%f*%f))*\"%(float(counter), float(counter-1),          


        

Answer 1

You appear to have found a bug in eval where it can't handle insanely long expressions:

>>> eval("1.0*"*10000+"1.0")
1.0
>>> eval("1.0*"*100000+"1.0")
# segfault here

I use the phrase "insanely long" advisedly though. Don't do it that way, calculate the pieces as you go. There is no reason to be using eval in this situation.

Answer 2

Why use eval() at all?

def pi(times):
    val = 1
    counter = 0
    for x in range(times) :
        counter += 2
        val *= float(counter)**2/(counter**2 - 1)
    return val * 2

Does the exact same thing.