Hi Preben

Functional differentiation, within the Physics package, rather advanced mathematical functionality, is all implemented exploting this feature, syntax like f(a)(b). Whether there is one example where a = b I think is not the core issue: suppose I come with one and answer you, then you will tell me "interesting", and I will reply "indeed, with time I got convinced that these rare syntaxes could be used with imagination in surprisignly useful ways" and I believe that in this hypothetical conversation you will end up agreeing. Now remove the "one example" and you can see you don't need the example to agree.

All in all, I don't know what torleian meant with f(t)(t), but that is valid syntax, the system should not crash, and that is what I fixed (actually a nice improvement in the design/logic of these Physics types), and now is up to torleian to make sense of his/her own computation.

Best

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

Updating this post: Today we added 52 more solutions and derived information to the database, so the current total is  679 solutions, and moving forward .... The metrics added today are from Chapter 23.

As usual, in order to have this new development installed right away, you need to update your Physics library from the Maplesoft R&D Physics webpage.

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

Hi Preben

The syntax is in use in the library, e.g. D(f)(t); the evalapply command is related to this syntax, it is handy for a number of purposes, although it is more a sort of computational artifact, mostly useful for performing computational/structure manipulations.

Best

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

There is a problem somewhere though; I am giving a look, but I am kind of overloaded with stuff in this moment. I'ill try to fix this problem and upload the fix between today and tomorrow.

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

@Christopher2222 

Above your last comment: there is a better version of the workaround that works in general posted earlier.

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

Hi

In order to help you it is kind-of-mandatory to be able to reproduce the problem. I see you are using the Physics package but I do not see how are you doing it, nor whether you are using the latest version (avialble on the Maplesoft R&D Physics webpage)

So could you just run a worksheet where the problem happens, and as soon as it happens save the worksheet and attach it to your post (you can edit your post, then click that green vertical arrow to attach a file) or clice the "Reply" button and attach the worksheet. From there we will probably be able to resolve the issue whatever it is.

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

@Christopher2222 , @acer 

I updated the workaround posted earlier today with a simpler version of it, that should also work in versions so older like Maple 12, and that automatically resolves the convert / frontend / type, etc. issues you mentioned Acer. Of course one may prefer to wait until an official patch for Maple 2015 is available. But if I were worried today or have a version of Maple prior to Maple 2015, I would install the workaround with no worries.

@Axel Vogt 

Thanks for your kind comments :) Best.

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

@Christopher2222 

Above your comment there is a workaround that works in general, and does not require loading Physics.

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

@Christopher2222 

There is a workaround that works for all of Maple 2015 <-> Maple 9.5 and does not require loading the Physics package.

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

Download workaround.mw

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

@ThU 

Indeed solving algebraic equations that involve objects noncommutative with respect to `*` would be an excellent addition to Physics. And indeed is in the plans. I don't know if you are following the path: first we added `*`, `^` and diff, then Gtaylor, Simplify, next was Expand, followed by Normal, Coefficients, and more recently Factor. All these are Physics commands; they perform the corresponding operations on algebraic expressions involving noncommutative objects. In addition we moved some of this functionality directly into expand, combine and simplify, the lowercase standard Maple commands.

In view of A*B <> B*A, however, these are complicated algebraic problems. The recent introduction of Physics:-Factor, on the other hand, is a very promising development in connection with "solving algebrai expressions that involve noncommutative operators". I don't think this will be ready for the next Maple release though. Still, some first approach for this functionality will most probably be in place in the near future.

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

Updating this post: Yes we are aware of the "100 years of Einstein's presentation of the theory of general relativity", and today we added 58 more solutions to the database, now totaling 627 solutions, already in the pole position and stepping on the gas towars digitized and bringing alive in the context of the Physics package, all the metrics collected in the classic book "Exact Solutions to Einstein's equations, (2nd edition)". The metrics added today are from Chapters 22 and 23.

As usual, in order to have this new development installed right away, you need to update your Physics library from the Maplesoft R&D Physics webpage.

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

Download UnitVectors_(reviewed).mw

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

Updating this post: Today we added 77 more metrics to the database of solutions to Einstein's equations, totaling 569 solutions at this point, according to the plan of having in the database, digitized and alive in the context of the Physics package, all the metrics collected in the classic book "Exact Solutions to Einstein's equations, (2nd edition)". The metrics added today correspond to Chapters 21 and 22.

As usual, in order to have this new development installed right away, you need to update your Physics library from the Maplesoft R&D Physics webpage.

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

@J F Ogilvie 

Thanks for your kind comments :) But please let’s not forget that general relativity (GR) is indeed part of physics, and this post just happened to be about that, which doesn’t mean that physics in Maple is only about GR.

As people using the package know, Physics has basic and advanced functionality for Quantum Mechanics since it entered the Maple library, including a full implementation of anticommutative and noncommutative operators and functions, related operations (including functional differentiation), Commutators, Anticommutators, Creation and Annihilation operator commands, pre-defined and customizable algebra rules, a whole implementation of Dirac notation for vector calculus on a space of quantum physical states, … to mention but a few; the list of functionality available is really large.

Perhaps it is useful to point to some application examples on Quantum Mechanics posted in this Mapleprimes forum in the past, developed using the same Physics package (that today implemented this most thorough digital database in existence for solutions to Einstein's equations):

• Quantum Mechanics using Computer Algebra 
• Quantum Mechanics (II)
• Superfluidity in Quantum Mechanics

The following link is also interesting because it shows a balanced set of applications in different physics areas, and the section on Quantum Mechanics also features a subsection on the use of the Physics package in developing proofs regarding properties of operations between quantum operators, something I don't recall having seen before in any computer algebra system, commercial or brewed at universities

• Computer Algebra for Theoretical Physics

For completeness, this other link to a mini-course on computer algebra for physicists is somehow ambitious, in that it shows an entry point to using such a wide-range-of-areas package as Physics is, while at the same time it is a compact tutorial for people who - simply put - never used computer algebra

• Mini-Course: Computer Algebra for Physicists 

Regarding your suggestion on updating the values of the fundamental constants, we have been working on this too and also have good news: mainly the incorporation of the CODATA 2010 updates to these constants. This is not distributed with the Physics package updates though, since this development is - at the company - unrelated to the one of Physics.

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