[wp34s] Poly root finders?

[emece67]

I've been tinkering with this PRS solver for a while. It definitely works quite nicely and even outperforms some other "multiple-root aware" solvers I've tested in Matlab.

After studying the code, now I feel confident enough to understand the way it works and even to modify it to better suit my needs (mainly, accepting complex coeffs). Well, I think I understand it except for the very last lines.

Code:


511 SCI 09
512 ROUND
513 STO Y
514 x[<->] L
515 ALL 00
516 ROUND
517 x=? Y        // round 10-digits=12-digits?
518 STO Z        // round x to 'rational' number
519 [cmplx]DROP

What are they for?