function varout = pt1m(varin,T)
%
%varout = pt1(varin,T)
%Einfacher PT1 Filter T*y' + y = u
%
%varin = [t, Messwert] .....


sz = size(varin);
if (sz(1)~=2 || sz(2)~=2)
    varout=0;
elseif sz(2) == 2
    varin=varin';
end

xD = varin(:,1); yD =  varin(:,2);
h  = mean(diff(xD));

yv(1) = yD(1);
yrd   = flipud(yD);
yr(1) = yrd(1);

for k = 1:(numel(xD)-1)
    yv(k+1,1) = h/T * (yD(k) - yv(k)) + yv(k);
    yr(k+1,1) = h/T * (yrd(k) - yr(k)) + yr(k);
end %k

size(yv)
size(yr)
yr = flipud(yr);
ym = mean([yv yr]')';
varout = [yv, yr, ym];