function error = lsqError(parameter, x, y)
% Objective function for fitting a linear equation to data.
%
% Arguments: parameter, vector containing slope and intercept (1st and 2nd element) 
%            x, the input values
%            y, the measured system output
%
% Retruns: the estimation error in terms of the mean sqaure error

y_est = x .* parameter(1) + parameter(2);
error = meanSquareError(y, y_est);