function E = gg250_lab9_misfit (x, y, a, b, mode)
% GG250_LAB9_MISFIT  Calculate misfit of a straight line
%
% E = gg250_lab9_misfit (x, y, a, b, mode)
% Input
%       x, y: a set of (x,y) coordinates
%       a, b: Coefficients for the line y = a*x + b
%       mode: How to measure misfit:
%             0 = Mean Square of vertical distances
% Output:
%       E:  The measure of misfit in units of y-squared.

e = y - (a.*x - b); % The residuals
E = sum (e .* e) / length (e);% Mean squared error