One of Profit's most powerful abilities is that it can ``fit'' a spectrum, automatically identifying and fitting features. We caution users that line fitting is a complex problem, which profit has only begun to address. Currently, profit attempts to fit the spectrum shown in the Main Plot Window using a straight line for the continuum and a series of Gaussians for line emission. The algorithm can be confused by a spectrum with many lines, a curved continuum, or simply a small number of counts in each bin. These problems are intrinsic to non-linear fitting and should not be considered ``bugs'' per se. However, the code works well when there are only a small number of well-separated lines with 20 or more counts and a flat continuum.
Due to the difficult nature of non-linear fitting and the many different combinations of machines and operating systems that can run profit, it is possible that profit will take a very long time to complete a fit, or even crash, if asked to fit a large region with many features, or one that cannot be easily fit with the simple profit model of a continuum plus Gaussians.