Re: Function Fit to 3D data set

*To*: mathgroup at smc.vnet.net*Subject*: [mg57796] Re: Function Fit to 3D data set*From*: dh <dh at metrohm.ch>*Date*: Wed, 8 Jun 2005 03:21:47 -0400 (EDT)*References*: <d83eh8$o6e$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, to plot points on an irregular 2 dim. grid, you can use: DiscreteMath`ComputationalGeometry`TriangularSurfacePlot sincerely, Daniel Adrienne R 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[\\\"Moreâ?¦\\\", \ > 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! >