Add functions not supported by micropython

distribution.py

@@ -1,6 +1,29 @@
 import math
 
 
+def factorial(n):
+	"""
+	Computes the factorial of a number.
+	:param n: The number to compute the factorial of.
+	:return: Returns the factorial of the number.
+	"""
+	if n == 0:
+		return 1
+	for i in range(1, n):
+		n *= i
+	return n
+
+
+def combination(n, r):
+	"""
+	Computes the combination of n choose r.
+	:param n: The number of items.
+	:param r: The number of items to choose.
+	:return: Returns the number of ways to choose r items from n items.
+	"""
+	return factorial(n) / (factorial(r) * factorial(n - r))
+
+
 def bnd(x, n, p):
 	"""
 	Computes the binomial distribution.
@@ -9,7 +32,7 @@ def bnd(x, n, p):
 	:param p: Probability of success.
 	:return: Returns the probability of getting x successes in n trials.
 	"""
-	return math.comb(n, x) * p ** x * (1 - p) ** (n - x)
+	return combination(n, x) * p ** x * (1 - p) ** (n - x)
 
 
 def bnd_mean(n, p):
@@ -187,7 +210,7 @@ def hgd(x, N, n, k):
 	:param k: Number of successes in the population.
 	:return: Returns the probability of getting x successes in n draws from a population of size N with k successes.
 	"""
-	return (math.comb(k, x) * math.comb(N - k, n - x)) / math.comb(N, n)
+	return (combination(k, x) * combination(N - k, n - x)) / combination(N, n)
 
 
 def hgd_mean(N, n, k):
@@ -278,7 +301,7 @@ def pd(x, l):
 	:param l: Average number of occurrences.
 	:return: Returns the probability of getting x occurrences.
 	"""
-	return (l ** x * math.e ** -l) / math.factorial(x)
+	return (l ** x * math.e ** -l) / factorial(x)
 
 
 def pd_mean(l):