[wp34s] Poly root finders?
12-04-2015, 12:58 PM (This post was last modified: 12-04-2015 01:03 PM by emece67.)
Post: #9
 emece67 Senior Member Posts: 363 Joined: Feb 2015
RE: [wp34s] Poly root finders?
(12-03-2015 10:04 PM)BarryMead Wrote:  The REAL component of both roots IS ZERO. Either you are not reading the answers correctly, or the root solver you picked isn't handling complex answers very well.
Since this particular equation is only of degree 2 you could always solve it with the SLVQ funciton. Put 1 in Z, 0 in Y and 1 in X Representing the a, b and c coefficients of the quadratic equation, and press X.FCN SLVQ.

[...]

Immediately after the SLVQ step, the first answer appears in the display. (0 + i1)
When the answer is complex, the manual says the second answer is the complex conjugate of the first, so press CPX X.FCN CONJ then the second answer (0 - i1) appears in the display.

Thanks Barry. I've just double checked it. Polyroot.wp34s reports both roots to be real and, thus, reports their imaginary parts as zero (as their real parts).

I know about SLVQ, but I was looking for a poly solver I can trust in everyday use.

(12-04-2015 09:34 AM)fhub Wrote:  The final version 'PRS' is a quite long program (520 steps), and it was available in the 'HP Articles Forum' for some time

[...]

The program is quite sophisticated, it works for polynomials with degrees upto 39 (but only with real coefficients) -
if you're interested I could upload it again.

(12-04-2015 11:50 AM)Dieter Wrote:  No, that's not the last version. It lacks several changes and 34s modifications that were introduced later. The final version (AFAIK) is found in the library folder of the 34s package, and it's called polyroot.wp34s.

[...]

As far as I remember the program seemed to work fine. Maybe there is an error in the code you entered?

I have just downloaded the last SVN version of polyroot.wp34s, compiled and tested it with 4 different polynomials of the 2nd & 3rd degree (all with real coeffs). In all cases the program crashed with a -∞ Error. These tests were run in the Qt simulator.

I have not keyed-in the program, just used copy/paste (for the version in the articles forum) or replaced an old file with a new one (for the SVN version).

Still searching...

César - Information must flow.
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 Messages In This Thread [wp34s] Poly root finders? - emece67 - 12-03-2015, 06:22 PM RE: [wp34s] Poly root finders? - BarryMead - 12-03-2015, 10:04 PM RE: [wp34s] Poly root finders? - Thomas Klemm - 12-03-2015, 11:43 PM RE: [wp34s] Poly root finders? - fhub - 12-04-2015, 09:34 AM RE: [wp34s] Poly root finders? - Dieter - 12-04-2015, 11:50 AM RE: [wp34s] Poly root finders? - fhub - 12-04-2015, 12:04 PM RE: [wp34s] Poly root finders? - Dieter - 12-04-2015, 12:32 PM RE: [wp34s] Poly root finders? - fhub - 12-04-2015, 12:53 PM RE: [wp34s] Poly root finders? - emece67 - 12-04-2015 12:58 PM RE: [wp34s] Poly root finders? - fhub - 12-04-2015, 01:07 PM RE: [wp34s] Poly root finders? - emece67 - 12-04-2015, 01:23 PM RE: [wp34s] Poly root finders? - fhub - 12-04-2015, 01:30 PM RE: [wp34s] Poly root finders? - emece67 - 12-07-2015, 05:40 PM RE: [wp34s] Poly root finders? - fhub - 12-07-2015, 08:05 PM RE: [wp34s] Poly root finders? - walter b - 12-07-2015, 08:50 PM RE: [wp34s] Poly root finders? - emece67 - 12-07-2015, 09:59 PM RE: [wp34s] Poly root finders? - fhub - 12-07-2015, 10:56 PM RE: [wp34s] Poly root finders? - emece67 - 12-07-2015, 11:19 PM RE: [wp34s] Poly root finders? - Dieter - 12-08-2015, 06:49 AM

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