How can I fit data to a sine curve?

Given a set of data points, how can I find the curve of best fit if I know that this will be a sine curve and nothing else?

Answer 1

[John D'Errico]

I'll guess the model you want is as below, but use the curve fitting toolbox.

Your model might be defined as:

ft = fittype('sin((x - shift)/xscale)*yscale','coefficients',{'shift','xscale','yscale'})
ft = 
     General model:
     ft(shift,xscale,yscale,x) = sin((x - shift)/xscale)*yscale

Now just call fit to fit the model to your data.

mdl = fit(X,Y,ft,'startpoint',[shiftguess,xscaleguess,yscaleguess]);

Other toolboxes have similar capability, but not quite as easy to use as the CFTB. (Stats TB, optimization TB)

[Careniena Opem]

I do not have the curve fitting toolbox, but I do have stats and optimization.

Answer 2

[Star Strider]

See: Curve fitting to a sinusoidal function.

It just uses core MATLAB functions. No toolboxes needed at all.