%!function rf=ruff(xp)

pr=xp(1);
rr=xp(2);

k=1/2.2;!.4;
rt=2;
c=9.3*rr^.25;
s=c*pr^.5;
x0=23*rr^.33/pr^.33;
x=x0;
dx=1;
dg=0.1;
b=0;
rt=x/exp(k*s*(1-1/exp(x*pr./s)));
rf=x;

