MATLAB: How to fit a curve where it turns back

boomerang curvecurve fitting

Hi, i would like to fit a curve with:

x=[0 0.8 1.4 1.2 1]

y=[0.4 0.8 1.4 0.8 0.4]

However, when I try it with curve fitting app, it always ignore the sequence of x, turn out to be:

but I need it to be like this:

How to make it to follow the sequence given in x? Thank you

Best Answer

You can use tools like cscvn.

Or you can use my interparc tool, found on the file exchange, which has several alternative methods available.

And of course, you can write code to do the work yourself. The first two options are better choices though. Always look for high quality code that does what you need before writing it yourself.

Related Solutions

MATLAB: How to access the result of Curve Fit App in the workspace

Hi,

when you are in the fitting app right click on the model you want to export:

then choose all options:

now you have the model, output and goodness in your workspace. To access the coefficients of the fitted model use:

>> coeffvals = coeffvalues(fittedmodel)
coeffvals =
      0.3768    1.4162    2.3424

To get some values from the goodness (for example the R-square value) use:

>> r_square = goodness.rsquare
r_square =
      0.9985

like shown here:

Best regards

Stephan

MATLAB: How to combine those lines into a surface (plot3) to surface

See if this does what you want:

T_Mtx = ([1.4; 1.2; 1; 0.8; 0.6] * ones(1,10))';
SOI = xlsread('internal_2.xlsx', 1,   'A2:A11');
SOI_Mtx = SOI * ones(1,5);
for i=1:5
    T(:,i)= xlsread('Mohammad FAQIR internal_2.xlsx', i, 'D2:D11');
end
surf(T_Mtx,SOI_Mtx,T)
xlabel('Equivelent ratio');ylabel('Start of ignition "BBDC" (Degree)');zlabel('Torque')

I simplified your code a bit, as well.

Best Answer

Related Solutions

MATLAB: How to access the result of Curve Fit App in the workspace

MATLAB: How to combine those lines into a surface (plot3) to surface

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