c----------------------------------------------------------------------
	function expdens(r)
c produces a 3D exponential density, normalized to 1
c
c author: Kieron Burke, 5.12.99
c     in: r - distance from origin
c    out: return value of function: 3D exponential density at point r 
c  calls: --	
	implicit real*8(a-h,o-z)
	parameter(pi=3.1415926535897932384626433832795d0)