[Maxima] %i and (complex 0 1)

[Stavros Macrakis]

> Who knows who relies on (if (eq (caar x) 'rat) ......)
> or that sqrt(-1) is a symbol.

There are some other surprising things that would have to be done.

Is numberp(%i) true?  

subst(-%i,%i,...) is the usual way of calculating the complex conjugate.
subst would have to special-case %i (note that there is NOTHING in the
subst code that hints that it would need any special cases...).

Presumably part(1+%i,2) is easy, since nformat will have to be changed
anyway.  inpart will have to handle #c the way it handles rat, I
suppose:

  atom(1/2) => false
  inpart(1/2,2) => 2

Oops, I spoke too soon about "the way it handles rat".  See my bug
report 816808: substinpart(4,2/3,2)=>2/4 (!)