Pfthb

I'm trying to make a symbolic product of matrices to act on a vector and then reading the powers and the associated coefficients of the resulting polynomial in each entry.

For that, I defined dictionaries in which I finally get a key corresponding to the powers of the several variables of the polynomial and the associated coefficient as the value.

Now, it works fine for dimension d=2 and n=10 steps (applying a certain matrix T(d)*DFT(d) 20 times), but for d=2 and n=20 it takes an eternity to finish.

The problem is in the line prelim = Poly(fila*maxpol,syms).as_dict()

Is there any way to make it more efficient?

def Probabilidad(n,d=2,Vector=VectorInit):
 """Vector es tu estado incial"""
 NVector=((T(d)*DFT(d))**n )*Vector
 syms=symbols('a0:%d'%int(2**d/2))
 maxpol=prod([x**n for x in syms])
 x=
 y=
 for fila in NVector:
 prelim = Poly(fila*maxpol,syms).as_dict()
 x = tuple(deg - n for deg in key): prelim[key] for key in prelim
 y = k: abs(x.get(k, 0))**2 + y.get(k, 0) for k in set(x) 
 return y