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In statistics, signal processing, and time series analysis, a sinusoidal model to approximate a sequence ''Yi'' is: : where ''C'' is constant defining a mean level, α is an amplitude for the sine wave, ω is the frequency, ''Ti'' is a time variable, φ is the phase, and ''Ei'' is the error sequence in approximating the sequence ''Yi'' by the model. This sinusoidal model can be fit using nonlinear least squares; to obtain a good fit, nonlinear least squares routines may require good starting values for the constant, the amplitude, and the frequency. Fitting a model with a single sinusoid is a special case of least-squares spectral analysis. ==Good starting value for ''C''== A good starting value for ''C'' can be obtained by calculating the mean of the data. If the data show a trend, i.e., the assumption of constant location is violated, one can replace ''C'' with a linear or quadratic least squares fit. That is, the model becomes : or : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「sinusoidal model」の詳細全文を読む スポンサード リンク
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