User function plot problem

[lamarcagiuseppe93]

Hi to everyone,
I bought almost 2 day ago an hp prime caluculator, it has still the old firmware.
I need to use many time 2 functions that there aren't in hp prime, these functions are "rectangle function" and "triangle function", now they are easy to do so i programmed the prime like so:

EXPORT RECT1(X,A)
BEGIN
Heaviside(X+A/2)-Heaviside(X-A/2);
END;

for the rectangle function and in similar way the triangel function, now the point s that the functions works well but when i go to plot them the calculator takes some time, and when i plot many of them, traslate or something like that and then move the plot the calculator gets block and i'm forced to reset, now i don't think this is normal because the functions are really easy to plot, so maybe i'm getting wrong on something, any suggestion? Thanks for the help