diff --git a/src/shamira/fft.py b/src/shamira/fft.py
new file mode 100644
--- /dev/null
+++ b/src/shamira/fft.py
@@ -0,0 +1,106 @@
+import math
+import cmath
+
+
+def dft(p):
+	"""Quadratic formula from the definition."""
+	N = len(p)
+	w = cmath.exp(-2*math.pi*1j/N)  # primitive N-th square root of 1
+	x = [0]*N
+	y = [0]*N
+	for k in range(N):
+		x[k] = w**k
+		for n in range(N):
+			y[k] += p[n] * x[k]**n
+	return y
+
+
+def compute_inverse(N1, N2):
+	for i in range(N2):
+		if N1*i % N2 == 1:
+			return i
+	raise ValueError("Failed to find an inverse to {0} mod {1}.".format(N1, N2))
+
+
+def prime_fft(p, divisors):
+	"""https://en.wikipedia.org/wiki/Prime-factor_FFT_algorithm"""
+	if len(divisors) == 1:
+		return dft(p)
+	N = len(p)
+	N1 = divisors[0]
+	N2 = N//N1
+	N1_inv = compute_inverse(N1, N2)
+	N2_inv = compute_inverse(N2, N1)
+
+	ys = []
+	for n1 in range(N1):  # compute rows
+		p_ = [p[(n2*N1+n1*N2) % N] for n2 in range(N2)]
+		ys.append(prime_fft(p_, divisors[1:]))
+
+	for k2 in range(N2):  # compute cols
+		p_ = [row[k2] for row in ys]
+		y_ = dft(p_)
+		for (yi, row) in zip(y_, ys):  # update col
+			row[k2] = yi
+
+	# remap and output
+	res = [0]*N
+	for k1 in range(N1):
+		for k2 in range(N2):
+			res[(k1*N2*N2_inv+k2*N1*N1_inv) % N] = ys[k1][k2]
+	return res
+
+
+# arr = [9,8,5,3,8,4,9,7,0,9,5,6,6,2,4]
+# print(dft(arr))
+# print()
+# print(prime_fft(arr,[3,5]))
+
+"""
+def fft(x):
+    N = len(x)
+    if N <= 1: return x
+    even = fft(x[0::2])
+    odd = fft(x[1::2])
+    T = [cmath.exp(-2j*math.pi*k/N)*odd[k] for k in range(N//2)]
+    return [even[k] + T[k] for k in range(N//2)] + \
+           [even[k] - T[k] for k in range(N//2)]
+
+
+def fft_mixed(x, r1, r2):
+	A = dft(x)
+	for k0 in range(0, r2):
+		pass
+
+
+def bit_reverse(x, width):
+	y = 0
+	for i in range(width):
+		y <<= 1
+		y |= x&1
+		x >>= 1
+	return y
+
+
+def bit_reverse_seq(x):
+	n = len(x)
+	width = round(math.log2(n))
+	return [x[bit_reverse(i, width)] for i in range(n)]
+
+
+def fft2(x):
+	y = bit_reverse_seq(x)
+	n = len(x)
+	omegas = [(-2*math.pi*1j/n)**i for i in range(0, n)]
+	b = 1
+	while b<n:
+		for j in range(0, n, 2*b):
+			for k in range(0, b):
+				alpha = omegas[n*k//(2*b)]
+				u = y[j+k]
+				t = alpha*y[j+k+b]
+				y[j+k] = u+t
+				y[j+k+b] = u-t
+		b *= 2
+	return y
+"""