# cpython-withatomic / Lib / poly.py

The branch 'legacy-trunk' does not exist.
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52``` ```# module 'poly' -- Polynomials # A polynomial is represented by a list of coefficients, e.g., # [1, 10, 5] represents 1*x**0 + 10*x**1 + 5*x**2 (or 1 + 10x + 5x**2). # There is no way to suppress internal zeros; trailing zeros are # taken out by normalize(). def normalize(p): # Strip unnecessary zero coefficients n = len(p) while p: if p[n-1]: return p[:n] n = n-1 return [] def plus(a, b): if len(a) < len(b): a, b = b, a # make sure a is the longest res = a[:] # make a copy for i in range(len(b)): res[i] = res[i] + b[i] return normalize(res) def minus(a, b): neg_b = map(lambda x: -x, b[:]) return plus(a, neg_b) def one(power, coeff): # Representation of coeff * x**power res = [] for i in range(power): res.append(0) return res + [coeff] def times(a, b): res = [] for i in range(len(a)): for j in range(len(b)): res = plus(res, one(i+j, a[i]*b[j])) return res def power(a, n): # Raise polynomial a to the positive integral power n if n == 0: return [1] if n == 1: return a if n/2*2 == n: b = power(a, n/2) return times(b, b) return times(power(a, n-1), a) def der(a): # First derivative res = a[1:] for i in range(len(res)): res[i] = res[i] * (i+1) return res # Computing a primitive function would require rational arithmetic... ```