ecterrab

14225 Reputation

24 Badges

19 years, 222 days

MaplePrimes Activity


These are replies submitted by ecterrab

@nm

It is important to remember that dsolve is a top level command that, in several intermediate steps, calls the simplifier, the integrator, and many other operation-commands (factor, series, etc.) In my almost 30 years working with Maple, using it to work on mathematical ideas, I don't recall one occurrence where it was dsolve - itself - hanging.

In this example, you present a problem under simplify. Assuming you use Maple from a worksheet, one useful approach to detecting where the computational flow hangs is to click that "bug" icon, which opens a DEBUG window showing the sequence of steps up to the one where the flow is hanging.

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions

@acer 
I see no difference, with or without Physics, which is currently at v.1840 after some fixes in the Student ODE package (see other Mapleprimes answers by Austin Roche). This is what I see, including the line with(Physics)
 

restart

with(PDEtools)

with(LinearAlgebra)

with(Physics)

Physics:-Version()

`The "Physics Updates" version in the MapleCloud is 1840 and is the same as the version installed in this computer, created 2024, December 26, 12:58 hours Pacific Time.`

(1)

with(SolveTools)

undeclare(prime)

`There is no more prime differentiation variable; all derivatives will be displayed as indexed functions`

(2)

declare(u(x, t)); declare(U(xi)); declare(G(xi))

u(x, t)*`will now be displayed as`*u

 

U(xi)*`will now be displayed as`*U

 

G(xi)*`will now be displayed as`*G

(3)

T := xi = -V*t+x; T1 := u(x, t) = U(-V*t+x)*exp(I*(-k*x+t*w+theta))

xi = -V*t+x

 

u(x, t) = U(-V*t+x)*exp(I*(-k*x+t*w+theta))

(4)

P3 := diff(u(x, t), x, t)

diff(diff(u(x, t), t), x)

(5)

``

(6)

P33 := diff(u(x, t), x)

diff(u(x, t), x)

(7)

P333 := diff(P33, t)

diff(diff(u(x, t), t), x)

(8)

NULL


 

Download why_including_with(Physics).mw

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

Hi
It is not that "dsolve generates internal error" in that the problem is not related to dsolve. Starting from your tracelast, this looks like a subtle bug in the logic of IntegrationTools:-Indefinite:-Polynomial that results in calls to factor that keep repeating. Maybe we can include a fix for this problem in one of the next Physics Updates.

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

@vv 
The changes you see in the Updates are in the version of Maple that is under development. From that point of view, no, it is not experimental. In fact this is a Typesetting fix that inadvertently introduced a different problem (bug), reproducible also in the version under development. It is good that @nm noticed it. Regarding Maple 2024, the problem started with v.1835 of the Updates, so entering Physics:-Version(1834), works around the issue. I will upload a solution for Maple 2024 later today.

PS update: the problem is fixed in v.1838.
Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

Hi
Thanks for the kind comments. It was a difficult decision, but everything has an end, even an apparently "never-ending" career that has already been long, more successful, and more fun than I could have imagined. 

As Andrew's post says, I will continue to work on existing Maple code, including the Physics package - my first computational project at University - and the Maplesoft Physics Updates, though on a 'have time' basis.

In connection, some people were curious about the cherished projects Andrew mentioned, which I intend to continue developing on a 'have time' basis. They are the most important ones I developed at Maplesoft along all these years. Some symbolic packages, some numerical, lots of technical writing, some looking more like courseware. This is a list of these Maplesoft projects, including the names of co-authors and students that worked on them together, cut from the CV

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

@scallopedpancake 
Your attachment has problems. Try downloading it and you see it doesn't work.

What is needed: a Maple worksheet, termination ".mw" illustrating your problem. Important: The description in the mw needs to tell what you expected and what you received that does not match that - or else what you expected and have no idea of how to get it. And yes, a short example is simpler to follow and so understand than a long one. Thanks.

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

@segfault 

 

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft


Download Relative_sign_of_the_Lagrangian.mw

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

@Jamie128 
Yes. It is possible to use Physics:-LagranteEquations to get field equations for gravity by using a (modified gravity) Lagrangian. Check the attached version of the help page of LagrangeEquations - it is reproducible by installing the latest Physics Updates (open Maple and input Physics:-Version(latest)).

Download LagrangeEquations_PhysicsUpdates.mw

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

@nm 

A dot release is not a version ahead. You need to be clear about this. Only a few bug fixes enter the dot releases, fixes considered critical for one reason or another. The Physics Updates contain significantly more fixes than that, also developments (entirely absent from dot releases). So no, you do not have Maple 2 versions ahead.

About your comment regarding "... fixes for very old bugs", what is what you consider old? The fixes mentioned in this conversation are for bugs all of them newer than March 2024, this year.

Your statement about odetest hanging does not change what I said before. In that "odetest hangs" post of yours, first, you show it does not hang. Then you show that if you first interrupt computations using timelimit and assumptions, next a hang occurrs. Perhaps you are unaware that interrupting a computation in that way leaves fragments of results in caches. That does not usually generate problems, but sometimes it does. In particular, your problem in that post involves is, assume and coulditbe. As you probably remember, in some cases, is and coulditbe interrupt with an error the first time, then they do not. These nuances can produce problems as the one you mentioned, not a problem in odetest.

By the way, if you want to know what hangs, Maple offers the tracelast instruction - I already mentioned this to you before. That allows you to post the actual problem, which in your example is not a problem in odetest; if it were, then it would have hanged the first time. It is also not a problem in the Maplesoft Physics Updates, even if its presence uncovers a problem not noticed before - that sometimes happens, you know that too.

Then the way you wrote this post I am commenting, it does look like "why are the fixes found in the Physics Updates not present when I remove the Physics Updates?" For me, that indicates you are not clear about how this works. Maybe you were not clear of what a dot release is.

Anyway, I can see you expecting even more from the software; I don't share your expectation, the comments aim at explaining that.

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

The Maplesoft Physics Updates is a project that aims at bringing to the current Maple release fixes that are present in the version under development, as well as new developments in the areas of Physics, Differential Equations and Mathematical Functions. Somehow, your posts these days, @nm , either indicate you are not clear about that or perhaps you are trying to say something else?

In this one above, you say that a version of the Maplesoft Physics Updates fixed a reported problem (and, you know, also other problems not reported in Mapleprimes). Well, if you remove the Maplesoft Physics Updates, the problems that it fixes are not fixed anymore. I find that natural—what were you expecting?

I also mentioned other times that installing the Physics Updates may reveal a problem that was not apparent without it. Yes, that can happen—report the case. Depending on the problem, it may get fixed in one of the next versions of the Updates, or you may need to wait until the next release because, sometimes, other problems are seen as a higher priority. All this is known.

In summary, you have two options: install this Maplesoft Physics Updates package and have all those fixes and developments "in advance", or wait for them until the next Maple dot or full release (for Maple 2024, that would be next year).

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

@Hullzie16 
Nice reply. Attached are a few comments intercalated in your worksheet that may be of interest. Physics is an environment with a myriad of simplifications for the input. They are not necessary but make entering things easier.

Tensor_Respond_(comments).mw

Best!
Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

This ODE system is solvable with the existing dsolve. But there is a problem in simplify subroutines. Before calling dsolve, input debug(`simplify/RootOf`, statements = false, depth = 1) and you see, at the end, the line that causes `simplify/RootOf` to interrupt with the Error message you saw. It shouldn't happen. I will see to include a fix for this in the next or so version of Maplesoft Physics Updates for Maple 2024, and write again here.

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

@mehran rajabi 
In that case you can use PDEtools:-dcoeffs. What confused me and I imagine others is that in your question you said "[Given the equation] ... I want to calculate separately, c1,c2,c3,c4,c5" (in a computer algebra context, that has the meaning of performing some calculation) while, actually, you do not want to calculate anything, only extract the coefficients.

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

1 2 3 4 5 6 7 Last Page 1 of 63