From: SourceForge.net <no...@so...> - 2009-04-22 09:53:24
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Bugs item #2777231, was opened at 2009-04-21 03:58 Message generated for change (Comment added) made by willisbl You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2777231&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 - Integration Group: None >Status: Pending >Resolution: Invalid Priority: 5 Private: No Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: integrate(1/(a^2-x^2), x) wrong Initial Comment: (%i1) integrate(1/(a^2-x^2), x); yields wrong (%o1) log(x+a)/(2*a)-log(x-a)/(2*a) correct is log(x+a)/(2*a)-log(a-x)/(2*a) wxMaxima 0.7.6 Maxima version: 5.16.3Maxima build date: 22:48 8/24/2008host type: i686-pc-mingw32 ---------------------------------------------------------------------- >Comment By: Barton Willis (willisbl) Date: 2009-04-22 04:53 Message: Maxima's answer might not be what you want, but it's correct. Where defined, the functions log(x-a) and log(a-x) differ by a constant. Checking Maxima's answer, we have: (%i21) integrate(1/(a^2-x^2), x); (%o21) log(x+a)/(2*a)-log(x-a)/(2*a) (%i22) rat(diff(%,x)); (%o22) -1/(x^2-a^2) Maybe you would like to use logabs : true (%i23) integrate(1/(a^2-x^2), x), logabs; (%o23) log(abs(x+a))/(2*a)-log(abs(x-a))/(2*a) ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2777231&group_id=4933 |