From: Andrii S. <and...@gm...> - 2023-01-23 08:26:40
|
When I tried to test this behaviour, I used maxima --batch="solve-fail.mac" with "solve-fail.mac" containing the reported input. I also tried starting maxima and pasting the input manually--same result of course. So I think there are no values set for the 'orderless' variables. And yes, the fact that the equation is trivial makes me mad. I'll probably code smth like 'linsolve1' specially for my case (approximate iterative solution of a set of nonlinear polynomial equations), where I need many thousands of calls to [lin]solve. The fact that 'solve' is so slow (16 sec as reported by Barton Willis in CCL, 22 sec for me) is also very annoying. Actually 'linsolve' is much faster, takes about 1 sec. Why is it so? The manual for 'solve' says "solve [...] solves a system of simultaneous (linear or non-linear) polynomial equations by calling linsolve or algsys [...]". Thanks all for trying this out and for suggestions. Andrii Sokolov On Sun, 2023-01-22 at 10:58 -0800, Richard Fateman wrote: > . I found no error in maxima 5.45.1 using wxmaxima front end (which, > however, refused to display the result in 2D because of its length.) > > Could it be that some of those items in orderless() had previously been set to values? Note also > that solving for B10 > is particularly trivial since B10 occurs only once, as given. This kind of error usually depends > on some hidden > dependency, like a sqrt(b) in the expression. Since sqrt(b)^2-b is not obviously zero if sqrt(b) > is given a different and > unrelated symbolic name in the rational function system, there is an opportunity for missing > common factors and > a cancellation. > Thanks for reporting this. > RJF > > On Sun, Jan 22, 2023 at 9:36 AM Andrii Sokolov <and...@gm...> wrote: > > Dear all, > > > > Recently I was not able to use 'solve' for an elementary linear equation--- > > if 'orderless' was called before. The commands are invoked are the following > > (sorry for a lengthy input): > > > > orderless(w1, w2, W1, W2, k1, k2, g, f1, f2, K)$ > > > > eq : -%i*W1*B10 = K * ((%i*g*f1^3)/((%i*w1-%i*W1+k1)*((-%i*w1)+%i*W1+k1) > > [...] > > +((-w1^2)+2*w1*W1-W1^2+(2*%i*w1-2*%i*W1)*k1 > > +k1^2) > > *k2^2)$ > > > > solve(eq, B10); > > > > which spits out: > > > > PQUOTIENT: Quotient by a polynomial of higher degree (case 1) > > > > Also if the rhs includes '- %i*w2*B10-k2*B10' additionaly, it diagnoses > > 'case 2a' in the same PQUOTINENT message. In both cases 'solve' provides > > an answer if 'orderless' was not called. > > > > I played a bit removing different parts of the equation and it was unclear > > for me what causes an error. > > > > Could that be a bug? Probably related to https://sourceforge.net/p/maxima/bugs/3273/ > > and the discussion > > https://maxima-discuss.narkive.com/yE8zdESX/quotient-by-a-polynomial-of-higher-degree > > > > I use Maxima 5.46.0 with GCL 2.6.12 from the RHEL 8 repo. > > > > Regards, > > Andrii > > > > > > > > _______________________________________________ > > Maxima-discuss mailing list > > Max...@li... > > https://lists.sourceforge.net/lists/listinfo/maxima-discuss |