function alpha = simple_perceptron(X,Y,maxloop,ker);

%X is an array of ROW vectors

%TRAINx = X(trinds,:);
%TRAINy = Y(trinds,:);
%TESTx = X(teinds,:);
%TESTy = Y(teinds,:);
nx = length(Y);
%maxloop = 20; % in case data not lin. sep.
done = 0;
cnt = 1;
alpha = zeros(nx,1);
ERRS = [];
while ~done
  done = 1;
  for i=1:nx
    x_i = X(i,:);
    y_hat = compute_yhat(X,x_i,alpha,ker);
    if (y_hat ~= Y(i))
      done = 0;
      alpha(i) = alpha(i) + Y(i);
    end
  end
  cnt = cnt+1;
  done = done + (cnt > maxloop);
  
  % show performance
  Yh = compute_yhat(X,X,alpha,ker);
  e = mean(Y~=Yh);
  ERRS(end+1)=e;
  plot(ERRS); drawnow;
  
end
return