[WWdevel] Another Legacy answer checker

[Davide P. C. <dp...@un...>]

Folks:

I have added a new Parser-based answer checker to replace cplx_cmp  
ass part of the Legacy package.  Upate your pg/lib/Parser/Legacy.pm  
and pg/lib/Parser/Legacy directory to get it, then move pg/lib/Parser/ 
Legacy/PGcomplexmacros.pl to pg/macros and restart the server.  You  
can use $useOldAnswerMacros to control which version of the answer  
checker is used (as with num_cmp and fun_cmp).

This is a bit more delicate than the num_cmp or fun_cmp replacements,  
as the strict modes need to allow operations in some circumstances  
and not others, but I think I have it worked out.  Let me know if you  
see any problems.

A question arose when I was working on the strict-numeric modes.   
Both the original and the new versions accept e^(pi i), since there  
are no operations performed within the real numbers involved, but e^ 
(pi/2 i) is not allowed because of the division by 2.  Would it be  
reasonable to allow expressions of the form a*pi/b within the  
exponent even in strict_numeric mode?  Should there be new modes (or  
a new flag) to allow/disallow this?  The old checker would SHOW  
answers in this form, even though the student couldn't type them in  
that way (but the new one won't).

In any case, try out the new checker and see if it works for you.

Davide