From: SourceForge.net <noreply@so...>  20080516 15:40:53

Bugs item #1686457, was opened at 20070322 18:52 Message generated for change (Comment added) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1686457&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: Share Libraries Group: None >Status: Closed >Resolution: Rejected Priority: 5 Private: No Submitted By: Nobody/Anonymous (nobody) Assigned to: Mario Rodriguez Riotorto (riotorto) Summary: cspline does not work Initial Comment: Maxima version: 5.11.0Maxima build date: 12:25 2/10/2007host type: i686pcmingw32lispimplementationtype: GNU Common Lisp (GCL)lispimplementationversion: GCL 2.6.8 I am running Vista on a pc and using wxMaxima with p:matrix([1,0.8619948],[0.5,0.95802009],[0,1.0986123],[0.5,1.2943767]) cspline(p) gives (%o5) 9.14034523948868*10^22*( (71825435496803423232*x^3+215476306490410269696*x^2+407633004344606888418*x+1207048040965873240689)* charfun2(x,inf,0.5)+(102765973994457923520*x^3+154148960991686885280*x^2+ 376969355089246552430*x+1201937400000985205250)*charfun2(x,0,inf)+ (30940538497654500288*x^3+154148960991686885280*x^2+376969273915256356068*x+1201937400000985205250)* charfun2(x,0.5,0)) This is a free or natural cubic spline and x^2 terms are supposed to be zero for the infinite range parts and the middle part which is indicated by charfun2(x,.5,0) is the same as the part corresponding to charfun2(x,0,inf) is the same except for the x^3 coefficient.  >Comment By: Robert Dodier (robert_dodier) Date: 20080516 09:40 Message: Logged In: YES user_id=501686 Originator: NO Closing this report as "rejected". Mario, thanks for looking at it.  Comment By: Mario Rodriguez Riotorto (riotorto) Date: 20080515 13:54 Message: Logged In: YES user_id=1270759 Originator: NO I don't see any problems. The abscissas from the given points range from a=1 to b=0.5, and according to the definition of natural cubic splines, if p is the interpolation function, the boundary conditions are p''(a)=p''(b)=0; it's easy to check that the result given by cspline fits this restriction. I don't understand why "x^2 terms are supposed to be zero".  Comment By: Robert Dodier (robert_dodier) Date: 20080514 23:07 Message: Logged In: YES user_id=501686 Originator: NO I don't understand what is the problem here. When I try this with cspline I get foo : (.06565092800000027*x^3+.1969527840000008*x^2 +.3725906320000009*x+1.103283576) *charfun2(x,minf,0.5) +(.09393164799999938*x^3+.1408974719999991*x^2 +.3445629760000002*x+1.0986123) *charfun2(x,0,inf) +(.02828071999999911*x^3+.1408974719999991*x^2+0.344562976*x +1.0986123) *charfun2(x,0.5,0) and when I plot that via draw2d (explicit (foo, x, 2, 1), points ([1, 0.5, 0, 0.5], [0.8619948, 0.95802009, 1.0986123, 1.2943767])); I see the spline is a smooth curve which passes through the points. Can someone point out what is wrong here?  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1686457&group_id=4933 