# Measuring the 'purity' of a sine wave using FFT (Matlab)

• MATLAB
I have a range of sine waves I have obtained in an experiment.

I want to put a measure on the purity of these sine waves - how well the reproduce a theoretical sine wave.

Is there anyway I can analyse the FFT of the sine waves in Matlab and put a measure on the purity of the sine wave (e.g. by measuring the FWHM of the peak at the frequency of the sine wave)?

Thank you