C+
C NAME:
C	ElSunDistance
C PURPOSE:
C	Calulates Electron-Sun distance and angle Sun-Electron-Observer
C CALLING SEQUENCE:
	function ElSunDistance(ScSun,ScEl,Elo, SinChi)
C INPUTS:
C	ScSun	real	Observer-Sun distance
C	ScEl	real	Observer-Electron distance
C	Elo	real	elongation of line of sight (deg), i.e. angle between
C			observer-Sun and observer-electron directions
C			(Elo = 0 is the direction observer-Sun)
C OUTPUTS:
C	ElSunDistance
C		real	Sun-Electron distance (same units as ScSun and ScEl)
C	SinChi	real	Sine of angle Sun-Electron-Observer
C PROCEDURE:
C	Cosine and sine rule in triangle with Sun, Observer and Electron on
C	the corners.
C MODIFICATION HISTORY:
C	SEP-1996, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
C-
	    real	ScSun
	    real	ScEl
	    real	Elo
	    real	SinChi

	ElSunDistance = max(0.,ScSun*ScSun+ScEl*ScEl-2.*ScSun*ScEl*cosd(Elo))
	ElSunDistance = sqrt(ElSunDistance)
	SinChi = ScSun/ElSunDistance*sind(Elo)

	return
	end