@Axel Vogt The link is not working

@Carl Love This exactly what I was looking for. Thank you

@Carl Love mods does not work on real numbers ("analog")

mods(11.5, 10);
Error, invalid argument for modp or mods
NULL;

I object using frem because it took quite a while to figure out how to get a MapleSim (or other languages) style mod. Next time I need it I will probably not remember straight away (for compatibilty and code exchange reasons I have stopped making custom commands).

Therefore fmod would be a nice extension to Maple commands. I will suggest this

@dharr 

I was not clear. Imagine you have some code to review. Somewhere in the code

sol:=dsolve({odes,ics},numeric,...)

If sol was a module I could ask for the exports. Since sol is a procedure I cannot ask which variables are returned.

Take for example this code from one man 1.mw
and enter

sln(0.1);
interface(verboseproc = 2);
print(sln);
showstat(sln);

after execution of the worksheet

@WD0HHU 

I do not think that this is a bug. It is a general weakness of variable step solvers.

There is an option that should enforce an event with variable step solvers. Have a look here

?dsolve,numeric,Events

I had to abandon rewriting the mass equation with events because I could not immediately spot an example/description that fitted your case.

Could you share a screen shot of the final trajectory?

By the way, I was wondering if such simulations could not profit from the Physics package which allows for a vectorial description of the problem which could save some lines of code.

@GFY 

This question is often asked.
I have only read the programming guide that comes with Maple. It's not really a book for learning.

Try searching here on MaplePrimes, and if you don't find anything, ask here, with topics that interest you.

@Scot Gould @Carl Love
Thank you for the clarification.

I overlooked that mod works on more than numbers. I also did not pay attention to the fact that mod works for "digital clocks" only but not for "analog clocks". I could not find an equivalent command that works on floats. Do I really have to do something like this

fmod := (t, modul) -> frem(t - 1/2*modul, 10) + 1/2*modul;
plot(fmod(t, 10), t = 0 .. 100);

One example, where this is extensively used is phase wrapping in signal processing. (I could use arctanxy for this, but that is also not straight forward).

By the way MapleSim does not restrict mod to integers

Looks like an infinite loop

@one man 

Thank you. I have to study this. What I learnd so far:

It's about common solutions of a system of equations.

Already the bivariate case can be non-trivial

@Thomas Richard 

The example from vv nicely shows how a parameter (velocity, acceleration, jerk,...) could be overlayed on a path. A usefull addition if it can be combined with a color bar.

vv example also shows that only expert users can do such things at the moment.

@mmcdara 
Intersting: I did not know that the color option accepts the plot structure COLOR. Is that an undocumented feature?

The problem (for choosen numerical parameters) is ill-conditionned because it can be reduced to

which has no solution appart from the a trivial one where a__1=0 and c__1=0 (which solve cannot find).
However, the way to solve, that I have provided below, should give solutions for other numerical parameters. Here is an updatad version using exact numbers
nonlin_sys.mw

@GFY

Yes, that is what I meant by: "For equation 3 you get in the same way 2 more equations sets of solutions".

These solutions are only valid for a subset of equations: equation 3, and equation 2, and equation 4.

I did not check if there is in all subsets of solutions a theta_3 that fullfils equation 1 and 3 at the same time.

We are dealing here with a complex argument which is beyond my comfort zone

FunctionAdvisor(plot,tan)

It seems that the real part of the two different solutions for theta__3 is Pi/2 spaced appart.

@acer 

I would not call it a bug. It comes with the design of the labels. Can't the labels be turned on permanetly in help pages. Its essential information when referred to. I use them allot in techincal documentation.

I cannot reprocude the mixed input of 1D Math and 2D Math.

I did in a rather new Maple session (Maple started in 2D):

?D  -> changed to 1D view -> copied the input -> new worksheet -> pasted the input