function y = symconv(x,h,type,fl,keep)
if strcmp(type,'row')
    y = conv2(x,h);
    y = y(:,1:2:end);
    y = y(:,fl/2 + 1:fl / 2 + keep(2));
else
    y = conv2(x,h);
    y = y(1:2:end,:);
    y = y(fl / 2 + 1:fl / 2 + keep(1),:);
end