HP solver has some bugs  Printable Version + HP Forums (https://archived.hpcalc.org/museumforum) + Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum1.html) + Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum2.html) + Thread: HP solver has some bugs (/thread69880.html) 
HP solver has some bugs  Will  02282005 try to find a root for 25*x5*ln(x)=0 using the hp49g solver...
Re: HP solver has some bugs  Mike (Stgt)  02282005 Plot it from x=0 to .5 and tell us what you expect.
Ciao.....Mike
Re: HP solver has some bugs  Gene  02282005 Well, it shouldn't return 0.2 something. :)
Gene
Your example does not suggest a problem...  Karl Schneider  03012005 "will"  My 33S also can't find a real root to your equation. I suspect that neither can my 15C, 28C, 32SII, 34C, 41C*/Advantage, 42S, 48G or 49G. Mike and Gene might be coy, but I think you really meant,
25*x+5*ln(x)=0, for which x = 0.26534
 KS Edited: 1 Mar 2005, 12:42 a.m.
World's all solver has a bug  or not???  Tizedes Csaba [Hungary]  03012005 My favourite, I posted it below, but NOBODY can tell me, what is the problem in the symbolic solvers!!! Heyhooo Mathematica, Maple, etc programmers!!!! Here is the little problem, what can solve an 10 yrs student, but your 10 yrs old symbolic progs CANT!!!!! Here it is:
1 1 Feed your head!
Csaba
you are right and you are not  Mike (Stgt)  03012005 True, your function at x=5 is _not_ defined. But (!) the root is a "hebbare Lücke" (sorry, I know only the German word; about "repealable or liftable gap") as the values of the function and its derivative at x=50 and x=5+0 are the same. But I am quite sure that no CAS cares about adjacence of gaps in a function.
Ciao.....Mike
Re: Your example does not suggest a problem...  axel  03012005 y=25*x5*ln(x) has no real solution, whereas y=25*x+5*ln(x) can be solved by HP Solver (tried on 32sii and 40g, solution is 0.2653449...)
Regards, Re: World's all solver has a bug  or not???  Will  03012005 Interesting posts...the bug is that the HP solver shows a false answer around 0.2 something which is not a root...in fact there is not real answer...
about the problem that csba told us is quite important avoid divide by 0.
Re: HP solver has some bugs  cyrille de Brébisson  03012005 Hello,
Actually, the solver works perfectly well.
If you try the "OLD" version of the equation solver UI:
Cyrille
Actually...  John  03012005 All one has to do on the new solver is press the menu label "INFO" and it will indicate that the 0.2 was found as an Extremum. This is ALWAYS a good idea and is proper use of the solver. One should never! accept a numerical result from a solver without knowing this type of additional information. Always press INFO to find out how the result was obtained!
Gene
Re: HP solver has some bugs  Bernardo Vargas  03022005 The problem is that SOLVE starts with the value x=0, and then returns immediately an error message because of the impossibility of ln(0). In this case the SOLVE program on the MATH1 module for the HP41 works better, since it asks first for two GUESSES for the solution. This way you can avoid the ln(0) by entering 0.1 or something like that. Then the program runs for some seconds and gives the answer ROOT IS 0.265344933. The manual of the HP32SII has an interesting appendix telling how SOLVE works, and explains some of its limitations.
And let me remind you that EVERY numerical algorithm has its limitations. So is mathematics, sorry.
which version/revision?  Mike (Stgt)  03022005 Aha! HP listens to the grapevine  Bon jour CdB! :) Could you pls tell us on which ROM version the "old" UI is available? I tried (i) Version HP49C, Revision #1.18 (no difference between redshift 7 and holdredshift 7), (ii) Version HP49B, Revision #1.196 (same as i), and (iii) Version HP49C, Revision #1.24 but there I was not able to reproduce your example. Suppose you are on a HP49G+plus. BTW, sorry if I ask for info that is described elswhere and I did not find it: what is the meaning of version letters on the HP49G? It seems not to correspond with the revision numbers. B=Beta and C=produCtion?
TIA.....Mike Edited: 2 Mar 2005, 9:18 a.m.
