anyone knows why my program is not giving result?

import copy
class Polynomial(dict):
    def __init__(self, coefficients):
        self.coeff = coefficients

    def dictionary(self,x):
        sum=0.0
        d=self.coeff
        for k in d:
            sum +=d[k]*x**k
        return sum
    def __add__(self, other):
        new=copy.deepcopy(self)
        for k,d in other.coeff:
            if k in new:
               new[k] +=value
            else:
                  new[k]=value
   开发者_运维知识库     return Polynomial(new)

p = Polynomial({20:1,1:-1,100:4})
q = Polynomial({1:1,100:-3})

print q+q

Iterating over a dict yields keys, not items.

for k, value in other.coeff.iteritems():

    for k in d:
        sum +=d[k]*x**k
    return sum

change to

    for k, v in d.iteritems():
        sum +=v*x**k
    return sum

EDIT: I see the problem...

in __add__(), value is not defined therefore it gets set to None and no result will happen