The error message is caused by Maples integration algorithm that calls the subroutine int/hermiter/horowitzLog 

infolevel[int]:=3;# up to 5 for more details

int(G, [xi = 0 .. infinity, eta = 0 .. 1]) assuming (0 < omega, 0 < b, 0 < x)

@Rouben Rostamian  

and very instructive. I see your point that for a given rotation axis first two more (Euler) angles must be determined before a rotation can be performed (proivided that the right rotation matrix is used with the correct sign of the angles).

Maple should have this easy way of rotation built-in.

Thank you

Interestingly the help page of simplify does not define what a simple expresion is.

It could be that simplify does not consider changing the argument of trig functions.

I would have expected simplify,size to do this because here the user input is clear about what kind of simple is wanted.

There might be expressions where simplify,size calling combine automatically would exclude other possible simplifications an expert could desire and for this reason it did not work.

Just a guess...

@chkat 

If I interprete correctly, Maple kernels (mserver) terminate external processes but the GUI does not do that.

The behaviour might be OS dependend. You use Linux. Correct?

Could you upload demo code that works under Windows?

By "closing the Maple window" you mean crtl-F4 or crtl-shift-F4 or close tab (right click on tab) or exiting the Maple seesion (i.e. the GUI, Alt-F4).

@one man 

It is possible to simulate rolling without slipage with MapleSim. Sometimes unreasonable high values for parameters of the contact have to be used. The problem is that no slip detector is available in MapleSim. Only in rare cases slip can be detected. This make simulation nice to look at but limits the interpretation. Slip equals wear and that is of interest.

Here it took me a while to reproduce an ideal rolling case.

I had no time for a code review. You say:Then we look at where its current location on the trajectory should be

Does this mean that the trajectory is given? By that, do you mean the trajectory of the contact point?

@Rouben Rostamian  

Then it looks like as if the output is not properly generated.

Thank you for the explanations. I would love to see Maple supporting quaternions.

This is a nice animation that raises a question: Are there initinal conditions that reverse the direction of travel of the small torus inside the large one?

Too bad that MapleSim does not allow a torus inside a torus contact. Simulating this with Maple is tempting but would take allot of time. Maybe there are other trustwothy alternatives that could be employed to find such solutions.

@Andiguys 

The problem is complex. In those cases answers might be obtained by restructuring expressions. The expression P in Simple_T can be converted to a factored expression: P=t1*t2*t3 .
These factors can be investigated separately and you might be able to extract meaningful relations. Here is one for t1 telling us conditions when t1 is positive and that apparently t1 cannot be negative. Now you have to combine this result with solutions for t2 and t3 and identify realtions for the parameters. In the best case you can derive form these realtions ranges for parameters (using solve).  There are quite some combinations to be investigated.
I now have to work on a less intersting task but I hope this helps to advance. It's not exculded that this problem can be boiled down to something meaningfull.

Download Simple_T_rply.mw

Interrupt works in screen reader.

Looks to me that the interrupt does get through to the kernel.
To interrup: Click on the bug icon an then quit and you are back to normal.

@nm

When my laptop runs on battery it switches to a balanced mode which limits tasks running full steam on the processor and the graphics card. This leads to Maple running slower. I assume that in the case we are discussig simplify was interupted by timelimit before this dll is called

What I see is that the dll is still active: the offset adress pointer (yellow) is still changing its adress.

Whatever simplify has asked the dll to do, it seems to be in an infinite loop. No new memory is allocated which is often the case in other instances where Maple "hangs" but effectivley an algorithm piles up result after result without comming to an end.

If timelimit would accept an instruction limit or processor cycles instead of a real time limit, a termination would be more deterministic.

My hypothesis is that Maple cannot termiate (all?) third party dlls. mserver.exe (including timelimit) is waiting for the dll to terminate. All functions in the stack of mserver wait for the above functions to terminate.

This case should be debugged.

@nm 

I had the same question. Maybe the sqrt expressions causes the call.

By the way:

I wanted to have a look at the stack again and restarted Maple.

This time the system ran in optimized battery mode. Simplify was interrupted before the call to GMP. If timelimit would work on CPU time this would not have happend. Maybe an option you could profit from and easier to implement than a true realtime kernel. I guess...

It hang's here:

If the page ?GMP is relevant then it could be that the hang is in a third party library and timelimit cannot/ does not terminate the call to this library.
Note: No memory piling up is visible which I see often when Maple becomes unresponsive.

Something must be special about "e".

@acer 

I used the form in the past but did not get feedback. I find the form not appropriate in cases where it is unclear whether a command performs as intended or where I do not want/need a software change. In those cases initial, informal clarification is helpfull.

For the future development of the Physics package: Where can/should observations (not necessarily bugs) made with the package be reported? 

Does it always make sense to contact Maplesoft support in any case?