Pythonで総和を実装 ref: http://qiita.com/SheepCloud/items/b8bd929c4f35dfd7b1bd

file0.txt

\sum_{i=m}^{n} f(x) = f(m) + f(m+1) + \cdots + f(n) \\

sigma.py

def sigma(m, n, func, s = 0) :
    if m > n: return s
    return sigma(m + 1, n, func, s + func(m))

sigma_test.py

print(sigma(1, 10, lambda x : x))
55

print(sigma(1, 3, lambda x : 3 * 5 ** (x - 1)))
93