Hi This thread is long - some messages got unnoticed. You are right, please see my reply yesterday, entitled "RE: Hi again, I progress only", second paragraph. Edgardo S. Cheb-Terrab Ph.D Theoretical Physics, Research Fellow, Maplesoft

Hi This thread is long - some messages got unnoticed. You are right, please see my reply yesterday, entitled "RE: Hi again, I progress only", second paragraph. Edgardo S. Cheb-Terrab Ph.D Theoretical Physics, Research Fellow, Maplesoft

Hi Robert, Indeed, this got implemented in connection with the Physics package for Maple 11, and it was possible to extend it to everything with essentially no cost. In the rush we missed documenting the feature, that I think is a great one. Edgardo S. Cheb-Terrab Ph.D Theoretical Physics, Research Fellow, Maplesoft

Hi Robert, Indeed, this got implemented in connection with the Physics package for Maple 11, and it was possible to extend it to everything with essentially no cost. In the rush we missed documenting the feature, that I think is a great one. Edgardo S. Cheb-Terrab Ph.D Theoretical Physics, Research Fellow, Maplesoft

Hi, Assuming that you use Maple 11, see ?Physics,examples, first section on Vectors and analytical geometry: there are a number of very similar worked examples that you can take as starting point to resolve the problem you posted. Edgardo S. Cheb-Terrab Ph.D Theoretical Physics, Research Fellow, Maplesoft

Hi We are taking care of 1, 2 and 3 for Maple 12 in agreement with your opinion. Regards Edgardo S. Cheb-Terrab Ph.D Theoretical Physics, Research Fellow, Maplesoft

Hi It works for me, i.e.: > restart; with(Physics); > A := matrix([[a, b*I],[c*I,d]]); [ a I b] A := [ ] [I c d ] > Dagger(A); [ _ _] [ a -I c] [ ] [ _ _ ] [-I b d ] > Dagger(convert(A, Matrix)); # also OK with Matrix [ _ _] [ a -I c] [ ] [ _ _ ] [-I b d ] ... so I guess I am missing something. Could you please post the input lines that don't work? Thanks. Edgardo S. Cheb-Terrab Ph.D Theoretical Physics, Research Fellow, Maplesoft

Hi It works for me, i.e.: > restart; with(Physics); > A := matrix([[a, b*I],[c*I,d]]); [ a I b] A := [ ] [I c d ] > Dagger(A); [ _ _] [ a -I c] [ ] [ _ _ ] [-I b d ] > Dagger(convert(A, Matrix)); # also OK with Matrix [ _ _] [ a -I c] [ ] [ _ _ ] [-I b d ] ... so I guess I am missing something. Could you please post the input lines that don't work? Thanks. Edgardo S. Cheb-Terrab Ph.D Theoretical Physics, Research Fellow, Maplesoft

Hi Could you be more especific regarding "anything you like"? I followed your steps, replaced _ by v and no error appeared. Edgardo S. Cheb-Terrab Research Fellow, Maplesoft

Hi, dsolve(des union ics); is sometimes returning a solution, other times not. The reason for that is that this is a system with three unknowns, and at the time of uncoupling the system there are six different ways of doing so, and only two of them lead to a solvable problem. This also tells what the workaround is ... But let's see the problem first: for R in combinat:-permute([x1,x2,x3]), try dsolve(des union ics, R(t)) and you will see that only when x3 comes in the last position in R is that the uncoupled linear system is solvable in current Maple. So the workaround is to give the ranking R basically saying "which unknown should be solved in terms of which other" (see explanations of rankings in ?PDEtools:-casesplit and elsewhere). For example, this returns a solution always: > dsolve(des union ics, [x1, x2, x3](t)); ... solution here ... # Verify that the solution solves the system and matches the initial conditions > odetest(%, des union ics); {0} Edgardo S. Cheb-Terrab Research Fellow, Maplesoft Editor for Computer Algebra, Computer Physics Communications

Hi, dsolve(des union ics); is sometimes returning a solution, other times not. The reason for that is that this is a system with three unknowns, and at the time of uncoupling the system there are six different ways of doing so, and only two of them lead to a solvable problem. This also tells what the workaround is ... But let's see the problem first: for R in combinat:-permute([x1,x2,x3]), try dsolve(des union ics, R(t)) and you will see that only when x3 comes in the last position in R is that the uncoupled linear system is solvable in current Maple. So the workaround is to give the ranking R basically saying "which unknown should be solved in terms of which other" (see explanations of rankings in ?PDEtools:-casesplit and elsewhere). For example, this returns a solution always: > dsolve(des union ics, [x1, x2, x3](t)); ... solution here ... # Verify that the solution solves the system and matches the initial conditions > odetest(%, des union ics); {0} Edgardo S. Cheb-Terrab Research Fellow, Maplesoft Editor for Computer Algebra, Computer Physics Communications

Hi I am not sure whether I am following the thread correctly, but dsolve(des, ics) cannot be correct. The DEs and Initial Conditions should be given in one and the same set, as R.Israel shows. Edgardo S. Cheb-Terrab Research Fellow, Maplesoft Editor for Computer Algebra, Computer Physics Communications

Hi I am not sure whether I am following the thread correctly, but dsolve(des, ics) cannot be correct. The DEs and Initial Conditions should be given in one and the same set, as R.Israel shows. Edgardo S. Cheb-Terrab Research Fellow, Maplesoft Editor for Computer Algebra, Computer Physics Communications

Hi, I replied to those threads some minutes ago - no it is not somewhat expected that things die unresolved :) Seriously speaking, sometimes it is easy to reply fast, other times not, for unforeseeable reasons. But we normally catch up and it is a pleasure to debate the features and design of this exciting Physics project, BTW unique in the existing computer algebra systems. Edgardo S. Cheb-Terrab Research Fellow, Maplesoft Editor for Computer Algebra, Computer Physics Communications

Hi Could you be more explicit on the computation you want to do? Generally speaking, with Physics in Maple 11 you can operate with tensors in flat spacetime, that can also be quantum operators, anti or non commutative variables etc. The algebra of Dirac matrices and a representation for them, as well as for Pauli matrices, come with the package, Traces of expressions involving products of these objects are also computed and the algebraic perturbative expansion underlying a sequence of Feynman diagrams is also computed using the Physics:-FeynmanDiagrams command. Besides that, Fundiff performs functional differentiation and, you know, you can perform functional integration in terms of Functional differentiation provided that we are interested in the perturbative expansion of the object. I used Physics for a number of QFT computations and in fact the precursor of this package is called QFT. Having said that, many things are still to be done, like returning the actual Feynman graphs, not the analytical expression behind them, providing complete representations for spinors of different types, making the package handle curved spaces, supersymmetry notation, and other etc. The package is evolving into that direction. So if you could make more explicit what is the computation you have in hands, depending on what you post it may be possible to do some or all of it already in Maple 11. Edgardo S. Cheb-Terrab Research Fellow, Maplesoft Editor for Computer Algebra, Computer Physics Communications