Factor a polynomial using the roots

polyfactor.py

#!/usr/bin/env python
# Polynomial Root Finder
# SYZYGY-DEV333
# Apache 2.0

step = 0.001 # smaller steps are more accurate, but slower
start = -10 # these parameters should be fine at -10 and 10
stop = 10

print "Python Polynomial Factoring"
print "use ** to mean ^"
print "Format: a*x**j + b*x**k + c (not ax^j+bx^k+c)"
print "examples: x**2 - 2*x - 24 ,  3*x**3 + 2*x**2 + x +3"

while 1 == 1:

	print

	equ = raw_input("0 = ") # asks for your equation

	f = lambda x: eval(equ,{"__builtins__":None},{"x":x}) # for saftey, won't accept anything other than an equation

	sign = f(start) > 0

	z = start
	while z <= stop:
		value = f(z)

		if value == 0:
			print "(x +", z, ")"
		elif (value > 0) != sign:
			print "(x +", z, ")"
		sign = value > 0
	 
		z += step

Polynomial Factoring using Python

This script is based on my Rootfinder, but factors it instead. I wrote it for my math class because doing it by hand is a pain. So yeah, this works. Saved me a lot of time.

How to install

Run the following commands in your Unix terminal:

wget http://bit.ly/1Pm0Gcs -O polyfactor.py
chmod +x polyfactor.py

Then you can run the program with ./polyfactor.py.
Have fun!