Get my X and Y values from curve fitting tool

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Shree Pannaga
Shree Pannaga 2023-1-13
编辑： Matt J 2023-1-13
First of all i´m completely new on matlab so forgive me if this is a dumb question... I had a curve fitting problem for my project and curve fit was completed using using custom fit equation and got a very nice fit.
The equation used for curve fitting was Y=1-((1-(X)^B)^A). R2 value I got around 95% and the co-effiecent value I got was A =0.6454 (0.5501, 0.7407) and B =0.1164 (0.09036, 0.1425)
Now I need the values of the X axis and Y axis Data of the fitted curve so I wonder if there is a fast and simple way to get them.
Please reply to my question immedieately. Any help will be appriciated.
  2 个评论
Shree Pannaga
Shree Pannaga 2023-1-13
function [fitresult, gof] = createFit(CycleRatio, Damage)
%CREATEFIT(CYCLERATIO,DAMAGE)
% Create a fit.
%
% Data for 'untitled fit 5' fit:
% X Input: CycleRatio
% Y Output: Damage
% Output:
% fitresult : a fit object representing the fit.
% gof : structure with goodness-of fit info.
%
% See also FIT, CFIT, SFIT.
% Auto-generated by MATLAB on 13-Jan-2023 20:08:19
%% Fit: 'untitled fit 5'.
[xData, yData] = prepareCurveData( CycleRatio, Damage );
% Set up fittype and options.
ft = fittype( '1-(1-(x)^B)^A', 'independent', 'x', 'dependent', 'y' );
opts = fitoptions( 'Method', 'NonlinearLeastSquares' );
opts.Display = 'Off';
opts.Lower = [-1 -1];
opts.StartPoint = [0.779167230102011 0.530797553008973];
opts.Upper = [1 1];
% Fit model to data.
[fitresult, gof] = fit( xData, yData, ft, opts );
% Plot fit with data.
figure( 'Name', 'untitled fit 5' );
h = plot( fitresult, xData, yData );
legend( h, 'Damage vs. CycleRatio', 'untitled fit 5', 'Location', 'NorthEast', 'Interpreter', 'none' );
% Label axes
xlabel( 'CycleRatio', 'Interpreter', 'none' );
ylabel( 'Damage', 'Interpreter', 'none' );
grid on

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回答（1 个）

Cameron
Cameron 2023-1-13
编辑：Cameron 2023-1-13
If you are using the Curve Fitting App, go to Export in the top right and select Export to Workspace. Then select OK, and your information should be in the fittedmodel variable.
fittedmodel.p1
fittedmodel.p2
%or
fittedmodel.A
fittedmodel.B
  2 个评论
Shree Pannaga
Shree Pannaga 2023-1-13
Hello Mr. Cameron, Thank you for the answer. But in my problem I am getting the variable values A and B oncee the fitting is created. My problem is I want to get the values of X axis and Y axis data after I finishes the fitting.
Matt J
Matt J 2023-1-13
编辑：Matt J 2023-1-13
The fitting process does not generate any X,Y data post-fit. However, the fittedmodel object that you export can be used to evaluate the fitted curve at any X values you wish. For example, if xdata,ydata are the data that you used to perform the fit, then you could do,
X=linspace(min(xdata), max(xdata),1000);
Y=fittedmodel(X)

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