Least squares sinusoid fit algorithm described in IEEE Standard for Digitizing Waveform Recorders (IEEE Std 1057): Algorithm for three-parameter and four-parameter least squares fit to sinewave data using matrix operations.



The algorithm is (in most cases) really quick. If the signal frequency is a guess, it has to be close to true frequency value.



For further information, consult IEEE Std 1057 and/or IEEE Std 1241 documentation.



Now also fits complex sinusoids i.e. phasors with noise and o