def BU(A, B, P): #radix-2 butterfly unit
tmp_ay = np.zeros((1, 2), dtype=int) #tmp_array
tmp_a = Mod.AddMod(A, B, P)
tmp_b = Mod.SubMod(A, B, P)
tmp_ay[0][0] = tmp_a #a+b
tmp_ay[0][1] = tmp_b #a-b
return tmp_ay
def NTT(x,ROU,prime,n,inverse): #output is a numpy array
IN = Mod.InvMod(n,prime) # calculate inverse multiplication of n
x = x % prime
y_list = []
for i in range(n):
acm = 0 #accumlation
for j in range(n):
exp = Mod.MulMod(i,j,n) #calculates power of i*j
tmp = Mod.ExpMod(ROU,exp,prime) #calculates w^(i*j)
tmp = Mod.MulMod(x[j],tmp,prime) #calculate x[j]w^(ij)
acm = Mod.AddMod(acm,tmp,prime)
y_list.append(acm)
y = np.array(y_list)
if(inverse == 1):
y = y * IN
y = y % prime
return y
