Prints the binomial expansion of any power.

README.md

Binomial Expansion Script

Run this file on the command line using the python command with the sole argument being the power of (x+y) you wish to expand.

Example:

python binomialexpansion.py 3

Will output:

x^3 + 3x^2y + 3xy^2 + y^3

binomialexpansion.py

import sys

power = int(eval(sys.argv[1]))
strpower = str(power)
coeffs = []

if power == 0:
	print 1
	exit()

if (power+1) % 2 == 0:
	turningp = (power+1)/2
	counter = 1
else:
	turningp = (power+2)/2
	counter = 2

for i in range(1, power+2):
	if i == 1:
		sys.stdout.write("x^"+strpower+" + ")
		coeffs.append(1)
		continue
	if i == power+1:
		print "y^"+strpower,
		coeffs.append(1)
		break

	if i > turningp:
		co = coeffs[turningp-counter]
		counter = counter+1
	else:
		co = ((power-(i-2))*coeffs[i-2])/(i-1)
	
	coeffs.append(co)
	sys.stdout.write(str(co))

	if power-(i-1) == 1:
		sys.stdout.write("x")
	else:
		sys.stdout.write("x^"+str(power-(i-1)))

	if i-1 == 1:
		sys.stdout.write("y ")
	else:
		sys.stdout.write("y^"+str(i-1)+" ")

	sys.stdout.write("+ ")