Subject: solve(...) and unnecessary complex results
From: Raymond Toy
Date: Thu, 21 Feb 2008 19:51:18 -0500
herczegh at earthlink.net wrote:
> Hello folks:
>
> Concerning the roots of x^3-4*x+2 you can show that the complex roots are
> equal to the real roots by simplifying the list of complex roots with the
> command polarform(). polarform() prompts: Is x positive, negative, or
> zero? reply 0 You can apply polarform() to the list of roots returned by
> solve().
>
>
What do you actually get when you do this? What I get is a list of the
form [0 = r*exp(%i*theta)], for appropriate values of r and theta. I
can't easily tell that the result is real. And the fact that I have 0 =
foo seems not nice either.
Applying trigsimp to the result makes it pretty clear that the roots are
all real.
Ray