We study several one-dimensional step flow models. Numerical simulations sh
ow that the slope of the profile exhibits scaling in all cases. We apply a
scaling ansatz to the various step flow models and investigate their long t
ime evolution. This evolution is described in terms of a continuous step de
nsity function, which scales in time according to D(x,t)=F(xt(-1/gamma)). T
he value of the scaling exponent gamma depends on the mass transport mechan
ism. When steps exchange atoms with a global reservoir the value of gamma i
s 2. On the other hand, when the steps can only exchange atoms with neighbo
ring terraces, gamma=4. We compute the step density scaling function for th
ree different profiles for both global and local exchange mechanisms. The c
omputed density functions coincide with simulations of the discrete systems
. These results are compared to those given by the continuum approach of Mu
llins.