Re: bug in Interpolation[] of Mma 3.0

*To*: mathgroup at smc.vnet.net*Subject*: [mg5810] Re: [mg5767] bug in Interpolation[] of Mma 3.0*From*: Francisco Edmundo de Andrade <edmundo at lia.ufc.br>*Date*: Wed, 22 Jan 1997 00:44:15 -0500*Sender*: owner-wri-mathgroup at wolfram.com

On Sat, 18 Jan 1997, Gennady wrote: > In my calculation of Interpolation[] function with Mathematica 3.0 > I found the following bug. > > If I run a piece of code given below with Mma 3.0 on my PowerPC 9500/120 > and compare the ListPlot of the original array and the Plot > of its Interpolation function, I see that the interpolation is very > poor. There is a big bump between values of abscissa 1.6 and 3.4 > which certainly should not be there. > The integral of the interpolation function (computed in the last line > of the code) equals 33.838. > > If I run the same code with Mathematica 2.2 (on the same PowerPC), > I find that the bump disappears, and the visual agreement between > the ListPlot and the Interpolation function is much better. Also, > the integral now is 27.0384, rather than 33.838. > > It would be interesting to check if the same bug appears on other > computers/platforms. I have reported the bug to Wolfram Research. > > Gennady Stupakov. > > (*---- Mathematica code --------*) > testlist={{0., 4.037}, {1.689, 4.744}, > {3.379, 6.865}, {3.551, 7.637}, > {3.723, 9.563}, {4.157, 17.429}, > {4.251, 19.065}}; > fun=Interpolation[testlist]; > ListPlot[testlist,PlotJoined->True,DisplayFunction->Identity] > Plot[fun[s],{s,0,4.2},PlotRange->All,DisplayFunction->Identity] > Show[%,%%,DisplayFunction->$DisplayFunction]; > NIntegrate[fun[s],{s,0,4.251}] > (*------------------------------*) > > Dear Gennady, I observed that your assertation applies to Mathematica 3.0 for Windows 95. Maybe it is a general bug of the version 3.0 (?!) Edmundo