FUNCTION relc,glat

; This function computes the local earth radius based on the WGS-72
; ellipse, taking the geographic latitude as input.  It is modelled
; on the function RELC in GEOLB.FOR.

a=6378.1350D0
b=6356.7505D0
rlt=((glat<90.)>(-90.))*!DTOR
x=COS(rlt)
y=SIN(rlt)
c2=DOUBLE(x*x)
s2=DOUBLE(y*y)
r2=a*a*b*b/(a*a*s2+b*b*c2)
RETURN,FLOAT(SQRT(r2))
END