[CAES] (x^4-4*x^3+2*x^2+4*x+4) Exact factorization of Quartic Polynomial

[parisse]

(04-24-2016 11:15 AM)roadrunner Wrote:  I agree that exact solutions to 4 order equations have little value. However, I expected cfactor to switch to approximate mode automatically and give a warning when appropriate, such as csolve does; not just return the original equation unaltered. Example: when exact mode is checked, csolve((x^4-4*x^3+2*x^2+4*x+4) = 0,x) gives a warning, then supplies the approximate answer.

-paul

cfactor factors over the field of coefficients of the argument, it should not switch to approx mode like csolve because cfactor is a rewriting command (unlike csolve), the answer must be mathematically equivalent to the argument.

-> to compsystems:
I won't elaborate again on quartic equations, please read my explanations in some post on a similar topic here. Again, you can write yourself a user program to factor 4th order polynomials if you think it's that important.