calcuale ---- OverflowError：long int太大而无法转换为float

Question

en_1 = 1
n = 1
factorial = 1
invfactorial = 1
    while en_1 > 1e-6 :
        en = en_1 +invfactorial
        n = n + 1
        factorial = factorial * n
        invfactorial = float(1.0/factorial)
        en_1 = en 
print "e = %.5f"%en

我想通过此代码计算e，但它无法正常工作。

Answer 1

en_1 > 1e-6永远不会评估为True。 en_1变得越来越大。在某些时候，你最终得到的数字太大，Python无法处理转换。而是与invfactorial > 1e-6比较：

en_1 = 1
n = 1
factorial = 1
invfactorial = 1
while invfactorial > 1e-6:  # changed comparison
    en = en_1 +invfactorial
    n = n + 1
    factorial = factorial * n
    invfactorial = float(1.0/factorial)
    en_1 = en # don't need both en_1 and en

这可以简单得多：

e = n = fac = 1
while 1.0/fac > 1e-6:
    fac *= n
    e += 1.0/fac
    n += 1