Details

Nonlinear curve fitting is based on a mathematical concept of regression analysis, which tries to minimize differences between the fit and nearby data points (residuals). This can be done for any given type of function and a possibly unlimited number of variables. Mathematica can compute nonlinear regression to fit a model sinusoidal function

to a dataset, taking into account uncertainties associated with each data point separately. In the equation, is a radial velocity, is a Julian date (or phase), and , , , are adjustable parameters. It is clear that this function can be stretched and shifted along either axis, but not tilted sideways.