proposed revision of sum/product

Hello,

In collaboration with Barton Willis I've prepared a revision of the sum
and product functions. The major points are:

  - substitute a gensym for the index variable and make assertions
    (via assume) about the gensym index
  - evaluate the summand/productand

Here is a file which can be executed as batch ("rtestsum.mac", test);
and the source code which reimplements sum/product.
The code passes all tests except for two which involve concat (foo, i).

  http://maxima.sf.net/tmp-sum/rtestsum.mac
  http://maxima.sf.net/tmp-sum/sum-revision-20050807.lisp

These are some bug reports which seem to be related.
The first one in this list is the one which got us going.
I believe the other bug reports are all resolved at this point,
either by this new sum stuff or by other developments; however,
I haven't considered the other bug reports in detail.

http://sourceforge.net/tracker/index.php?func=detail&aid=1192935&group_id=4933&atid=104933
http://sourceforge.net/tracker/index.php?func=detail&aid=1007094&group_id=4933&atid=104933
http://sourceforge.net/tracker/index.php?func=detail&aid=851765&group_id=4933&atid=104933
http://sourceforge.net/tracker/index.php?func=detail&aid=740134&group_id=4933&atid=104933
http://sourceforge.net/tracker/index.php?func=detail&aid=649428&group_id=4933&atid=104933
http://sourceforge.net/tracker/index.php?func=detail&aid=625278&group_id=4933&atid=104933

Many thanks to Barton for his extensive work on this topic.
I look forward to any comments you-all may have.

Robert Dodier