How do I set DE?

[M Benesi]

  Say I want to set DE for a function to

DE = max (sqrt(x^2+z^2)-width, y-length);   

//  max (a,b);  returns the maximum value of a or b

  What do I write to (where in the memory... rout?? internal variables pointer +38h??), and which DEoption should I use? 

[DarkBeam]

Not possible except for DIFS