From: SourceForge.net <no...@so...> - 2004-02-22 21:26:12
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Bugs item #900860, was opened at 2004-02-19 22:53 Message generated for change (Comment added) made by macrakis You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=900860&group_id=4933 Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: Simplifications involving abs Initial Comment: abs(q)/q^2 and q^2/abs(q) currently don't simplify. These should simplify to 1/abs(q) and abs(q). This is especially useful since things like sqrt(q^2) simplify to abs(q). It would be even nicer if GCD understood this case, but I can understand that that would be harder, e.g. gcd(abs(q)+q^2,abs(q)) => 1+abs(q) This seems practically justifiable; is there any theoretical reason it might not be justifiable? ---------------------------------------------------------------------- >Comment By: Stavros Macrakis (macrakis) Date: 2004-02-22 16:16 Message: Logged In: YES user_id=588346 With declare(q,complex), q/abs(q) should presumably simplify to carg(q), except for the problems with that (620246, 902290). Assuming definition by continuity, q/abs(q) and carg (q) even have the same 'value' (ind) at q=0. With *real* r, r/abs(r) = signum(r) *except* at r=0, where the first is undefined, but the second is well-defined (=0). ---------------------------------------------------------------------- Comment By: Barton Willis (willisbl) Date: 2004-02-22 15:35 Message: Logged In: YES user_id=895922 When 'domain' is complex or q has been declared complex, the simplification abs(q) / q^2 --> 1/abs(q) shouldn't happen. Barton ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=900860&group_id=4933 |