I need to find a way to plug in unknown values into a function I curve-fitted to known data.

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Ryan McKee
Ryan McKee 2022-3-23
回答： Steven Lord 2022-3-24
I have a handful of 98x2 arrays that I'm treating as x and y values. The x values are unequally spaced, which is an issue in my case. My plan was to fit a curve to the x vs. y scatterplot using MATLAB R2020A's Curve Fitting app, utilizing the Smoothing Spline option. Once I fit the curve I planned to input my own custom (equally spaced) x-values into this fitted function and have the new y-values returned, which I would then build my new arrays out of.
I managed to fit the curve and it's accurate enough for what I'm using it for. However, I'm not sure what my next step is from here. I'm still a novice with MATLAB and learning a lot, but it's slow going. The fitted curve I generated doesn't appear to be a function that I can plug x values into, and I'm not certain how I would be able to tell the coordinates for each point. Is there a way for me to plug x-values into a fitted function such as this? Or rather an easier method that I've missed? Any and all help is very much appreciated, thank you!
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Torsten
Torsten 2022-3-23
编辑：Torsten 2022-3-23
If you had plain MATLAB code, we could help.
But I think you will have to read the documentation of the curve fitting tool to get your questions answered.

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回答（2 个）

John D'Errico
John D'Errico 2022-3-23
编辑：John D'Errico 2022-3-23
This is not as hard as you make it seem. (Honestly, I tend not to use cftool at all. I just use fit.)
Look at the menu options. Under the fit menu, you should see the option: "Save to Workspace". Click on that. You will now see a popup.
The popup allows you to save your model to a variable in your MATLAB workspace. Pick whatever name you want.
You can now use that returned result to evaluate the function at any chosen point.
Steven Lord
Steven Lord 2022-3-24
You can generate code or export the fit to the workspace. Once you've done that you can evaluate it or perform other postprocessing on it.

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