function y = predict(x,w)
% Y = PREDICT(X,W)
%
% Predicts based on a linear regression model using weights W
% X must be a matrix, with one input vector per row
% W must be a column vector of weights, witn number of elements
% equal the number of columns in X plus one.
  n = size(x,1);
  y = [ones(n,1) x] * w;
