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From: SourceForge.net <noreply@so...>  20060916 03:14:22

Bugs item #1552710, was opened at 20060905 08:27 Message generated for change (Comment added) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1552710&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core  Simplification Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: product(sum(f(i),i,1,inf),j,1,inf) => inf (wrong) Initial Comment: product(sum(f(i),i,1,inf),j,1,inf) simplifies to inf This is wrong. The simplest counterexample is f(i):=0, where the product = 0. If you want to get fancier, consider f(i):=2^i; product = 1. 5.9.3 Windows GCL  >Comment By: Robert Dodier (robert_dodier) Date: 20060915 21:14 Message: Logged In: YES user_id=501686 Changing the two instances of MGRP to MGREATERP in SIMPPROD1 (src/asum.lisp) makes this problem go away. MEVALP routes ((MGREATERP) ...) to the function MGRP (src/compar.lisp). I speculate the presence of MGRP (instead of MGREATERP) in SIMPPROD1 is an optimization. (MEVALP '((MGRP) ((%SUM) (($F) $I) $I 1 $INF) 1)) returns T, which is spurious, and which then leads SIMPPROD1 to conclude the product is infinite. MGRP refers to special variables ODDS and EVENS which is probably part of the problem. However, I confess that I don't fully understand what is going on. Grepping for MGRP, it looks like MGRP is called elsewhere. Maybe we should review the use of MGRP and friends.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1552710&group_id=4933 