maxima-bugs

 [Maxima-bugs] [ maxima-Bugs-932302 ] partfrac/ratnumer of taylor bad: taychk2rat/FIX From: SourceForge.net - 2004-04-09 14:05:01 ```Bugs item #932302, was opened at 2004-04-09 09:45 Message generated for change (Comment added) made by macrakis You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=932302&group_id=4933 Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) >Summary: partfrac/ratnumer of taylor bad: taychk2rat/FIX Initial Comment: expr: 1/(x^2-1)\$ texpr: taylor(expr,x,1,1)\$ ptexpr: partfrac(texpr,x) => (x+4/(x-1)-3)/8 NO! This is algebraically correct, but not in partfrac form. The correct answer is given by: partfrac(ratdisrep(texpr),x) == partfrac(ptexpr,x) => 1/(2*(x-1))+(x-3)/8 The immediate fix is to replace (DESETQ (RATFORM . EXP) (TAYCHK2RAT EXP)) with (DESETQ (RATFORM . EXP) (RATF (TAYCHK2RAT EXP))) however, I wonder if TAYCHK2RAT shouldn't be doing this. Compare: ratnumer(taylor(x+1/x,x,0,1)) => x+1/x ??? ---------------------------------------------------------------------- >Comment By: Stavros Macrakis (macrakis) Date: 2004-04-09 10:05 Message: Logged In: YES user_id=588346 taychk2rat is used in four places in Maxima: ratnumer ratdenom partfrac horner In all of them, it would be better if taychk2rat performed the ratf. So the fix should be in taychk2rat, not in the callers. Or maybe in \$taytorat. I don't understand what srrat does -- is that the problem? Maybe look at this later. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=932302&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-932302 ] partfrac/ratnumer of taylor bad: taychk2rat/FIX From: SourceForge.net - 2006-04-09 20:43:47 ```Bugs item #932302, was opened at 2004-04-09 07:45 Message generated for change (Settings changed) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=932302&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 - Taylor Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: partfrac/ratnumer of taylor bad: taychk2rat/FIX Initial Comment: expr: 1/(x^2-1)\$ texpr: taylor(expr,x,1,1)\$ ptexpr: partfrac(texpr,x) => (x+4/(x-1)-3)/8 NO! This is algebraically correct, but not in partfrac form. The correct answer is given by: partfrac(ratdisrep(texpr),x) == partfrac(ptexpr,x) => 1/(2*(x-1))+(x-3)/8 The immediate fix is to replace (DESETQ (RATFORM . EXP) (TAYCHK2RAT EXP)) with (DESETQ (RATFORM . EXP) (RATF (TAYCHK2RAT EXP))) however, I wonder if TAYCHK2RAT shouldn't be doing this. Compare: ratnumer(taylor(x+1/x,x,0,1)) => x+1/x ??? ---------------------------------------------------------------------- Comment By: Stavros Macrakis (macrakis) Date: 2004-04-09 08:05 Message: Logged In: YES user_id=588346 taychk2rat is used in four places in Maxima: ratnumer ratdenom partfrac horner In all of them, it would be better if taychk2rat performed the ratf. So the fix should be in taychk2rat, not in the callers. Or maybe in \$taytorat. I don't understand what srrat does -- is that the problem? Maybe look at this later. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=932302&group_id=4933 ```