RSquare Command

RSquare( <List of Points>, <Function> ): Calculates the coefficient of determination R² = 1 - SSE / Syy, between the y-values of the points in the list and the function values of the x-values in the list.

RSquare({(-3, 2), (-2, 1), (-1, 3), (0, 4), (1, 2), (2, 4), (3, 3), (4, 5), (6, 4)}, 0.5x + 2.5) yields 0.28.