;+ ; NAME: ; hgp ; PURPOSE: (one line) ; Compute a single parameter Henyey-Greenstein phase function. ; DESCRIPTION: ; CATEGORY: ; Mathematical ; CALLING SEQUENCE: ; ans = hgp(phase,c) ; INPUTS: ; phase - Angle between the incident and emitted flux (in degrees). ; c - Henyey-Greenstein functional value. ; OPTIONAL INPUT PARAMETERS: ; KEYWORD PARAMETERS: ; OUTPUTS: ; Return value is the phase function value(s). Same dimension as ; the inputs. ; COMMON BLOCKS: ; SIDE EFFECTS: ; RESTRICTIONS: ; PROCEDURE: ; MODIFICATION HISTORY: ; Written 1991 Feb.,by Marc W. Buie, Lowell Observatory ;- function hgp,phase,c return,(1.-c^2)/(1.0+c^2+2.0*c*cos(phase/!radeg))^1.5 end