Re: Function Fit to 3D data set

*To*: mathgroup at smc.vnet.net*Subject*: [mg57763] Re: [mg57748] Function Fit to 3D data set*From*: Chris Chiasson <chris.chiasson at gmail.com>*Date*: Tue, 7 Jun 2005 05:59:51 -0400 (EDT)*References*: <200506070603.CAA24471@smc.vnet.net>*Reply-to*: Chris Chiasson <chris.chiasson at gmail.com>*Sender*: owner-wri-mathgroup at wolfram.com

You might do well to look up TriangularSurfacePlot and DelaunayTriangulation if you want to make a surface from your points. http://documents.wolfram.com/mathematica/Add-onsLinks/StandardPackages/DiscreteMath/ComputationalGeometry.html It seems as if you have not followed the correct syntax for calling FindFit. Try adapting one of the examples to your case. On 6/7/05, Adrienne R <roehrich at unlserve.unl.edu> wrote: > I have been trying to do several analyses with an [x,y,z] data set, where z is dependent on x and y. First, I tried a 3D plot. However, the only way I was able to get Mathematica to plot my data was to assume a grid form for x and y, and use ListPlot3D. First question: can Mathematica make a 3D plot from stated x,y,z points? > > Secondly, I am trying to fit a function to the data. I have determined a function to which to fit parameters. However, Mathematica does not seem to want to accept y as a variable. Here is a simple suggestion of what I was trying. Note, my function is much more complicated. Please also ignore if the given does not work as stated, as I'm making it up. > > points = {{1, 1, 1}, {1, 2, 4}, {1, 4, 16}} > f1 = FindFit[points, a + b*x^0 * y^1 + c*x^0 *y^2 +k*x^2 *y^0 + l*x^2 * y^1, {a, b, c, k, l}, x, y] > > The error I receive is \!\(\* > RowBox[{\(FindFit::"nonopt > "\), \(\(:\)\(\ \)\), "\<\"Options expected ( > instead of \\!\\(y\\)) beyond > position \\!\\(4\\) in \\!\\(\[LeftSkeleton] 1 \[RightSkeleton]\\). An \ > option must be a rule or a list of rules. \\!\\(\\*ButtonBox[\\\"More?\\\", \ > ButtonStyle->\\\"RefGuideLinkText\\\", ButtonFrame->None, \ > ButtonData:>\\\"General::nonopt\\\"]\\)\"\>"}]\) > > Second question: Can Mathematica take a set of x,y,z data where z is dependent on x and y and fit a function to it? > > Secondary question for both: How? > > Thanks for the help! > > -- Chris Chiasson http://chrischiasson.com/ 1 (810) 265-3161

**References**:**Function Fit to 3D data set***From:*Adrienne R <roehrich@unlserve.unl.edu>