about surface plot and its code

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Pradeepta Sahu 2017-9-13

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评论： Walter Roberson 2017-9-13

I have plotted a surface using 3 variables from excel data and obtained a surface plot. How can I find a code for the generation of a dependent variable when i have two independent variables.

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KSSV 2017-9-13

Question is not clear.....

Rik 2017-9-13

It sounds to me like you have a 3D point cloud in an Excel file and would like to fit a function Z=f(X,Y). If this is the case, it is very difficult (if not impossible) to provide a general solution. You can use griddata if the points you want to interpolate are within your data range. If you want to extrapolate, things are more difficult, as some releases will return NaN values (which is badly documented behavior).

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Answer 1

John D'Errico 2017-9-13

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So you have generated a surface plot, thus a surface of the form z(x,y).

Now you want to find some simple "function" that can produce a value of z, for ANY intermediate values of x and y?

This is typically called surface fitting, although interpolation is another approach that can be employed. So you might use tools from the curve fitting toolbox, or you might choose to try tools like interp2 or scatteredInterpolant.

Exactly which tool you might use would depend upon the surface itself.

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Rik 2017-9-13

He enable contacting him on his profile (just click on his name to get there), but please don't. Helping on this forum is a hobby for most of us, answering e-mail is work. I you post your follow-up here, he (or anyone) can get to your question when we have time. Direct, personal contact is generally not a good idea for things like this, that's what you have teachers, offline friends and consultants for.