@MDD Yes, I suggest that you try assuming. You may need to resort to assume, which is a bit stronger. But if assuming does the job, I'd definitely use it instead. I think that it's a bit unusual to use assume inside a procedure because (I think) it has global effects.

@MDD Can you do what you want with assuming rather than assume (see my Answer)? An assuming clause only lasts for the duration of the command to which it's applied, and there are no ~. If you do need to change an interface setting from inside a procedure, you should change it back at the end:

save_showassumed:= interface(showassumed= 0);

... rest of procedure ...

interface(showassumed= save_showassumed);

...

end proc;

@MDD The ~ is there to show that the variable has assumptions on it, i.e., that it has been declared in an assume command. If you don't want to see the ~, you can give the command interface(showassumed= 0).

[This is a Question, not a Post, so I changed it to a Question.]

You say "obviously, it can be simplified," but it isn't so obvious to me. What exactly did you have in mind? One option is full expansion of the numerator. That could followed by collection with respect to any or all of the variables. Another option is simplify(..., size). None of these produces a significantly shorter expression.

@Qruze Is the new exercise randomly generated also? Then you can begin your "dovundet" with the commands

restart;
randomize():

and use the !!! button.

Your code looks right to me. I don't know why you say that you're "drawing a complete blank" when you've actually written correct code.

@KarryWC You should post, here on MaplePrimes, the exact steps that you took to get to this error message. Usually (not always), the person who tells you how to correct an error needs to be able to first reproduce the error on their own computer. Thus, they need to know the steps that you took to get to the error.

For example: "I entered the equation x=y+1; and pressed Enter. Then I right clicked on the output to get the context menu. I selected Manipulate Equation. The Equation Manipulator loaded without error."

@MDD The error message is too specific to answer that question. First, we need to know where `expand/power` is being called from. Executing trace(`expand/power`) before running your code might help determine that.

You should give the exact command or sequence of commands that you used to get to this error.

@Preben Alsholm Ah, that's been changed since Maple 16 (which I'm using right now).

@Markiyan Hirnyk I don't get your point. I get exactly the same blue output whether I use %piecewise, 'piecewise', or `print/piecewise`. Which are you saying is better?

@Axel Vogt I don't understand your point at all. Do you perceive the above as a bug? Why?

Furthermore, there is no "convention" about 0^1. It indisputably equals 0. Perhaps you are thinking about a convention regarding 0^0?

@Carmelo I'm sorry, but I don't understand your English "With eval does not made." Perhaps you should show the relevant output from Maple where something hasn't been "made".

Your question about extraction of results leads me to believe that you believe that dsolve has already computed the results and they're sitting is memory somewhere and you merely need to "extract" them. That's not true; the results aren't computed until you call num_n.

@vv Thank you for the example. It's certainly simple.

@vv Can you give me a simple example of an improper integral that becomes proper after a change of variables? one where after the change the integrand is entire?