function eval_smooth(Ta)

fs = 10000;

b = 1;
if (abs(Ta) > 0)
    b = 1/(abs(Ta)*fs);
end;

a = 1 - b;

x = [ zeros(1, 1000) ones(1, 1000) zeros(1, 1000)];

y = 0;
for i=1:length(x)
    if (Ta < 0)
    y = b*x(i) + a*y;
    yn(i) = y;
end;

plot(yn); grid;