Re: Extrapolation in mathematica
- To: mathgroup at smc.vnet.net
- Subject: [mg51549] Re: Extrapolation in mathematica
- From: DrBob <drbob at bigfoot.com>
- Date: Thu, 21 Oct 2004 22:21:42 -0400 (EDT)
- Reply-to: drbob at bigfoot.com
- Sender: owner-wri-mathgroup at wolfram.com
Just turn off the error message. For instance:
data = Table[x + 5Random[], {x, 1, 20}];
f = Interpolation[data];
Off[InterpolatingFunction::"dmval"]
Plot[f@x, {x, 0, 21}];
Extrapolations are usually meaningless, however--as a few trials of the code will clearly demonstrate.
For instance, the following fit is lousy outside the data range:
g = 2 - x + x^2 + x^3 + x^4;
data = Table[g, {x, 1, 20}];
f = Interpolation[data, InterpolationOrder -> 3];
Plot[{g, f[x]}, {x, -5, 0}]
But changing InterpolationOrder makes it perfect:
f = Interpolation[data, InterpolationOrder -> 4];
Plot[{g, f[x]}, {x, -5, 0}]
Bobby
From: brindaban at gmail.com (nilaakash)
To: mathgroup at smc.vnet.net
Subject: [mg51549] Extrapolation in mathematica
Organization: Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Dear
Anybody could you tell me how to extrapolate data in
mathematica. I can interpolate my data, but extrapolation is not
working.
Thanks.
nilaakash