Hello,

Any Calc experts around?  emacs -Q:

  M-x calc RET
  0 RET
  a i x RET

is a way to integrate 0 using Calc (with integration variable x in this
case).  Calc fails to solve it:

The result Calc gives you is "integ(0, x)" - Calc leaves the integral
unresolved, which is Calc's way to say "I can't solve this".  This
is definitely not a feature or a way to represent an integration
constant - (info "(calc) Integration"):

| Also, any indefinite integral should be considered to have an
| arbitrary constant of integration added to it, although Calc does not
| write an explicit constant of integration in its result.

So what is going on?  Other functions, including constants like 1 or a
symbol work as expected.

As far as I understand, Calc is internally perfectly able to solve this
integral but at one place in the code the correct result is rejected
because this case is so special that the authors forgot to make the code
expect a result of such a simple form.  This small change helps: