I've built a quartic calculator solver which finds the roots the long way. All math is included. I've done some testing on it for quartics with 4 real roots and quartics with 2 real and 2 imaginary roots. All math is included to find the roots similar to the method found on Wikiepedia. There is a truckload of math, so if you do skim through it, make sure you have a cup of coffee to keep you awake. The lesson is housed on the algebra page, and is searchable by quartic, equations, roots. Let me know if you see any errors, or want enhancements.
Soving Quartic Equations