PRO trsk1,plt,pln,pht,x,y,z

; Modelled on FORTRAN subroutine of the same name in GEOLB.FOR
; Angles input in degrees, converted to radians for computations

a=6378.135D0
b=6356.755D0
a2=a*a
b2=b*b
ep2=(a2-b2)/a2
cplt=COS(plt*!DTOR)
splt=SIN(plt*!DTOR)
cpln=COS(pln*!DTOR)
spln=SIN(pln*!DTOR)
tmp1=FLOAT(SQRT(1.0D0-ep2*splt*splt))
x=FLOAT((a*cplt*cpln/tmp1)+pht*cplt*cpln)
y=FLOAT((a*cplt*spln/tmp1)+pht*cplt*spln)
z=FLOAT((a*(1.0D0-ep2)*splt/tmp1)+pht*splt)
RETURN
END