def PolyInverseModOverQ(f: Poly, r: int): #r=2, предполагаем f0[0] = 1
f = f.trim()
if (r < 1):
raise ValueError
#f = modPoly(f, zn)
f0 = f.coef[0]
if (f0 != Fraction(1, 1)):
f0 = 1 / f0
if (f0 == Fraction(0, 1)):
return None
g = Poly(f0)
l = int(math.ceil(math.log2(r)))
for k in range(1, l + 1):
g = (2 * g - f * (g**2))
g = g.truncate(2**k)
return g
def PolyInverseModOverZn(f: Poly, r: int, zn: int): #r=2, mod zn r = log2
if (r < 1) or (zn < 1):
raise ValueError
#f = modPoly(f, zn)
f0 = f.coef[0]
if (not (f0 == 1)):
g = Poly(inverse(f0, zn))
else:
g = Poly(f0)
if (g.coef[0] == None or zn == 1):
return None
l = int(math.ceil(math.log2(r)))
for k in range(1, l + 1):
g = (2 * g - f * (g**2))
g = g.truncate(2**k)
g = modPoly(g, zn)
return g
