Re: [TS 3227] ListInterpolation

*To*: mathgroup at smc.vnet.net*Subject*: [mg23478] Re: [mg23467] [TS 3227] ListInterpolation*From*: Matt.Johnson at autolivasp.com*Date*: Fri, 12 May 2000 22:54:19 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Kurt- per the book: "Interpolation works by fitting polynomial curves between successive data points. " In other words, the curve pases through each data point input. If you have many data points, you probably need to increase the PlotPoints to see the noise in your original data. As for the derivatives, I have the same problem with my data. A smoothing routine that would accurately represent the major trends without the in-between small variances would be nice. -matt Kurt Taretto <Kurt.Taretto at ipe.uni-stuttgart.de> on 05/10/2000 10:54:16 PM Subject: [mg23478] [mg23467] [TS 3227] ListInterpolation Hi, I'm using ListInterpolation to get functions that smoothly describe my data. So the resulting plots are smooth lines that transverse my noisy data. When I try to plot the derivative of this functions, I get very sharp zig-zags (that I could also get deriving numerically my data). Mathematica is making an interpolation between my points, and since my points are noisy distributed, y also get the noise in the derivative. That's ok, but why do I get smooth plots that cross my data, say, at a "mean noise value". I cannot use NonLinearFit because the functions I need should be case sensitive and I have a large number of data sets, so choosing a fitting function every time could be extremely tedious. I'm sure there's a way out of this, if someone could help me, I'd appreciate any help. Thanks!