subroutine elled (xc,yc,a,b,h,ed,dndh)
c	s/r to calculate the electron density, ed, and slope, dndh' for
c	an elliptical profile --  see s/r ellipse
c
c	written by leo mcnamara 4-aug-87
c-----	last modified 4-aug-87
c
	y = h
	yb = (y - yc) / b
	con = sqrt (1. - yb*yb)
c	take negative sqrt to get correct part of ellipse
	con = - con
	ed = xc + a * con
	dndh = -a / con * yb / b
	return
	end