The nice addition added to Maple 2022 in this  post made it clear that c__1 and _C1 are the same under the cover.

But then why in Maple 2025.1 it does not give this?

I found this when I was trying to find constants of integrations in solution of an ode, and used 

                 indets(sol,And(symbol, suffixed(_C, nonnegint))); 

Which did not find the constants of integration, since I happened to have typed the solution using c__1 and not _C1, but I thought they are the same.

Did something change or I still dont understand well the difference between c__1 and _C1 ?

Worksheet below.

Download why_c1_and_C1_not_same_oct_19_2025.mw

Update

Found out why. This only works if one calls dsolve() first.  Here is an example

Download why_c1_and_C1_not_same_oct_19_2025_V1.mw

But this is really confusing. c__1 before calling dsolve is not the same as c__1 after calling dsolve.

It will be better if Maple is changed such that these work the same all the time without having to call dsolve() first.

Maple help does not have an example I could find showing the right way to call method, which is meant to be called only from the constructor the object, before the object is fully build.

Help page does not have such example.

This worksheet shows 3 possible ways to do this. All seem to work fine. I am sure one can come up with more variations.

The question is, which one of these calls is the "right" way?

The method called from the constructor in this example is called process_age().

If someone knows an official Maple documentation showing one example of calling  a proc from constructor that will also help.

Download correct_way_to_call_method_from_constructor_oct_17_2025.mw

Help page for structured types shows examples where they add delayed quotes around things. For example

So I started writing  'specfunc(anything,y)' instead of just  specfunc(anything,y). Only to find this breaks things when used inside a proc.

Here is an example.

Removing the quotes, it now works

Download delayed_vs_not_v2.mw

Download delayed_vs_not.mw

It took me 2 hrs debugging to find this, as when I copied code which was working in my worksheet to my function, it stopped working and did not know why.

So for now, I will not use quotes around specfunc or any others like the help page shows in its examples.

Is there a rule of thumb to follow here? The help page is very inconsistent. It shows some examples with quotes around and some without. Makes it hard to know why and when to add the delayed quotes. It seems arbitrary.

I gave up on this. I know how to find all normal derivatives such as diff(y(x),x) and diff(y(x),x$2) so on in expression. 

But now I want to find all those used for initial conditions, which do not have x in them. This makes it harder.

These have the form   D(y)(0) or (D@@2)(y)(1) and so on.

I tried indets and select and many other things, but can't figure how to tell Maple to find these in expression. Here is an example.

Given

expr:=y(3)+y(8)+5*(D@@2)(y)(4)+Pi+3*exp(2)+77*D(y)(0)+1/(D@@4)(y)(7);

I'd like to get list that has in it only the derivatives and nothing else, anywhere they show, which will be

{(D@@2)(y)(4) , D(y)(0) , (D@@4)(y)(7) }

some of the things I tried are

indets(expr,'satisfies'(s->op(0,s)=(D@@n)(y) and n::integer) );
indets(expr,'specfunc(anything, D)');
indets(expr,'specfunc(anything, (D@@anything)(y))');

And many more. I still struggle with structured types in Maple.

In the above, we can assume the dependent variable is always same which is the 'y' symbol.

I can do the above using patmatch. But I am trying to move away from that in Maple and use types.

For reference, this is what I do using another software. I am trying to do the same in Maple, but using structured types and not patmatch.

Iam sure there is a way to do this in Maple using structured types, but so far not able to figure the syntax needed.

Maple 2025.1

I have more examples like this. Sometimes odetest give false negative result. dsolve solution is actually correct, but odetest does not return all zeros as result of its checking.

Example 1

Download odetest_problem_oct_8_2025.mw

Would you agree that odetest in the above should have returned [0,0] instead? Should this result be considered a bug?

Example 2

More examples where odetest gives false negative. The solution by dsolve is correct but odetest says IC is off but it is not. 

Download odetest_problem_oct_11_2025.mw

Example 3

Download odetest_problem_oct_11_2025_V2.mw

Example 4

Download odetest_problem_oct_11_2025_V3.mw

Example 5

Download odetest_problem_oct_11_2025_V4.mw

Will add more examples as I find them....