# Discarding Outlying Points

As with the FitLine tool, the FitCircle and FitEllipse tools let you ignore some of the points you provide. The tools compute the fit using every possible combination of the points you supply after discarding the number of points to allow the tool to ignore. This has the effect of discarding outlying points:

Be aware the values you specify for the number of input points and the number of points to ignore can result in an extremely large number of possible combinations of points, especially when you specify a large number of input points and the difference between the number of input points and the number of points to ignore is large. In these cases, the tool may take considerable time, since it must fit and evaluate each point combination.