Is it possible to plot directly in cylindrical (or spherical) coordinates?

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I would also like to perform fits to this type of data without converting everything to Cartesian. Is this possible.

Thanks,
Richard
You are not telling us what connection you find between plotting and performing fits. Please provide more details so we can send you a more specific response.

A.G.
WaveMetrics, Inc.

November 27, 2010 at 12:14 pm - Permalink

I can't speak too much for the plotting side, but it's relatively easy to fit data obtained in spherical/cylindrical coordinates. You need to use the FuncfitMD or Gencurvefit operation to do the fit from a user function.
Your fit function would look something like this:

Function my2DFitFunction(w, zed, r, theta, phi) : fitfunc
// zed = f(r, theta, phi)
Wave r, theta, phi

//write out your z=f(r,theta, phi), e.g:

zed[] = r * sin(theta[p]) * cos(phi[p])

return 0
End

November 28, 2010 at 01:31 pm - Permalink

Igor wrote:
You are not telling us what connection you find between plotting and performing fits. Please provide more details so we can send you a more specific response.

A.G.
WaveMetrics, Inc.



There is no connection between fitting and plotting that I an concerned with. I really just want to plot a set of data in cylindrical and overlay the fit of that data.

Thanks,
Richard

November 29, 2010 at 06:43 am - Permalink

Richard_G wrote:
There is no connection between fitting and plotting that I an concerned with. I really just want to plot a set of data in cylindrical and overlay the fit of that data.

Thanks,
Richard

There certainly is no problem with performing fits in which the input variables are interpreted as theta, phi instead of x, y. I presume you want to make a polar plot of the result. I don't know if you have found the Polar Plot package yet- try Windows->New->Packages->New Polar Graph. The resulting control panel has a Help button on it.

You may need to add the fit result manually using the Polar Graphs panel rather than having it added automatically as would happen if you were using a regular graph.

John Weeks
WaveMetrics, Inc.
support@wavemetrics.com

November 29, 2010 at 05:27 pm - Permalink