Modulo function for making pulse train.

Hi,

Trying to make a pulse train by combining the heaviside function with the modulo function, as described in a previous post.

The heaviside works fine for one pulse:
(flc2hs(5- t),1)

But when I substitue t for the modulo function:
flc2hs(5- (mod(t,0.01)),1)
the function gives a constant output of 1.

Could someone explain to me what the modulo function actually does as it is not explained in the help files

Thanks for the help.