Update seteps.f90

correct sign

source/f90/seteps.f90

@@ -62,7 +62,7 @@ subroutine seteps(neps, nos, oscType, osc, epsinf, wn, eps, layers)
           wp = osc(1,k)
           y0 = osc(2,k)
           yp = osc(3,k)
-          addDrude = addDrude - dcmplx(wp**2, (y0 - yp) * wn) / dcmplx(wn2, wn * y0)
+          addDrude = addDrude - dcmplx(wp**2, (yp - y0) * wn) / dcmplx(wn2, wn * y0)
         case default
           write (*,'(A)') '*** Error in oscillator type! ***'
       end select