If you're trying to graphically determine at which value(s) of Na the
two curves are equal, try ginput.
> i made a *.m file with de next code
> I have ploted in logaritimic scale the functions, "E_rup_1" and
> "E_rup_2" depending off Na,
> on the plot and for a Na value, the 2 functions are equal.
> How can i get the Na value?