[GiNaC-devel] Improvements for algebraic substitutions.

[Chris Dams]

Happy new year!

I found out that if we do (notation simplified to be more readable but
less compilable):

(a^n*b^m*b^p).subs($0^$1*$0^$2==$0^($1+$2),subs_options::algebraic)

nothing happens because a^n already matches a factor in the pattern and
in that case no other matches are attempted. I fixed this.

Also, I allowed algebraic substitution to match multiple times on
different factors with the same pattern. E.g. the above .subs() can be
used to simplify

a^n*a^m*b^p*b^q -> a^(n+m)*b^(p+q)

These changes are in CVS.

Bye,
Chris