HeunC(-4*b, 4*b, 2, 8*b^2, -8*b^2 - _c[2] + 1, (-r + 2*b)/(2*b))
Is there a simple way in Maple to determine whether the following confluent Heun function terminates or when it terminates?

When doing variable change for a differential equation, dchange works well for transformations like {s=r sin(theta),z=r cos(theta)}, but it does not seem to work if you include constant values like {s=(k-1)*r sin(theta)}, how can I let maple know that k is to be treated as a constant?

Could someone help me fix this loop.

It is printing the expressions without evaluating but it is evaluating it before appending it to the list.
I do not want to apriori define the functional dependence i.e. f(t).

lis := [f1, f2, f3, f4, f5, f6, f7, f8, f9, f10];
L := [];
for i in lis do
    print(subs(f = i, 'diff(f, t)'));
    L := [op(L), subs(f = i, 'diff(f, t)')];
end do;
print(L);

I want to write an if statement with a matrix R:
such that maple executes command 1 if R is Matrix(4, 4, [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]])

and command 2 if R is not zero.

What is the easiest way to go about this?

I was wondering if there was a command that could tell me if an expression consisting of undermined functions was always positive (with real domain).

For example f1:=f(x)^2+g(y)^4 is always positive.

but f(x)^2-g(y)^2 is only positive on a restricted domain.