WSJT-X/map65/libm65/geocentric.f90
Bill Somerville 280c8344cd
Move project files to map65 sub-directory
Preparation for merging with the wsjtx project repository.
2021-04-09 13:57:41 +01:00

18 lines
421 B
Fortran

subroutine geocentric(alat,elev,hlt,erad)
implicit real*8 (a-h,o-z)
! IAU 1976 flattening f, equatorial radius a
f = 1.d0/298.257d0
a = 6378140.d0
c = 1.d0/sqrt(1.d0 + (-2.d0 + f)*f*sin(alat)*sin(alat))
arcf = (a*c + elev)*cos(alat)
arsf = (a*(1.d0 - f)*(1.d0 - f)*c + elev)*sin(alat)
hlt = datan2(arsf,arcf)
erad = sqrt(arcf*arcf + arsf*arsf)
erad = 0.001d0*erad
return
end subroutine geocentric