Fortran 95 source code to convert ECEF to WGS84(BLH) coordinate.

ecef2blh.f95

!*******************************************************************************
! ECEF -> BLH 変換
! : ECEF（Earth Centered Earth Fixed; 地球中心・地球固定直交座標系）座標を
!   WGS84 の緯度(Latitude)／経度(Longitude)／楕円体高(Height)に変換する。
!
!   date          name            version
!   2019.02.21    mk-mode.com     1.00 新規作成
!
! Copyright(C) 2019 mk-mode.com All Rights Reserved.
! ---
! 引数 :  X Y Z
!         (ECEF 座標)
!*******************************************************************************
!
program ecef2blh
  implicit none
  ! SP: 単精度(4), DP: 倍精度(8)
  integer,      parameter :: SP = kind(1.0)
  integer(SP),  parameter :: DP = selected_real_kind(2 * precision(1.0_SP))
  character(*), parameter :: USAGE = "[USAGE] ./ecef2blh X Y Z"
  real(DP), parameter :: A      = 6378137.0_DP           ! a(地球楕円体長半径(赤道面平均半径))
  real(DP), parameter :: ONE_F  = 298.257223563_DP       ! 1 / f(地球楕円体扁平率=(a - b) / a)
  real(DP), parameter :: B      = A * (1.0_DP - 1.0_DP / ONE_F)  ! b(地球楕円体短半径)
  real(DP), parameter :: E2     = (1.0_DP / ONE_F) * (2.0_DP - (1.0_DP / ONE_F))
                                                         ! e^2 = 2 * f - f * f
                                                         !     = (a^2 - b^2) / a^2
  real(DP), parameter :: ED2    = E2 * A * A / (B * B)   ! e'^2= (a^2 - b^2) / b^2
  real(DP), parameter :: PI     = atan(1.0_DP) * 4.0_DP  ! 円周率
  real(DP), parameter :: PI_180 = PI / 180.0_DP          ! 0.0174532925199433
  real(DP) :: x, y, z       ! ECEF 座標
  real(DP) :: lat, lon, ht  ! BLH  座標

  ! コマンドライン引数(X, Y, Z)取得
  call get_arg(x, y, z)
  if (x == 0) stop
  print '("ECEF: X = ", F12.3, "m")', x
  print '("      Y = ", F12.3, "m")', y
  print '("      Z = ", F12.3, "m")', z

  ! ECEF -> BLH
  call conv_ecef2blh(x, y, z, lat, lon, ht)

  ! 結果出力
  print '(A)', "--->"
  print '("BLH: LATITUDE(BETA) = ", F12.8, "°")', lat
  print '("  LONGITUDE(LAMBDA) = ", F12.8, "°")', lon
  print '("             HEIGHT = ", F12.3, "m" )', ht

  stop
contains
  ! コマンドライン引数(X, Y, Z)取得
  !
  ! :param(out) real(8) x: X
  ! :param(out) real(8) y: Y
  ! :param(out) real(8) z: Z
  subroutine get_arg(x, y, z)
    implicit none
    real(DP), intent(out) :: x, y, z
    character(20) :: a

    x = 0.0_DP
    y = 0.0_DP
    z = 0.0_DP
    if (iargc() < 3) then
      print *, USAGE
      return
    end if
    call getarg(1, a)
    read (a, *) x
    call getarg(2, a)
    read (a, *) y
    call getarg(3, a)
    read (a, *) z
  end subroutine get_arg

  ! ECEF -> BLH
  !
  ! :param(in)  real(8)   x: ECEF 座標 X
  ! :param(in)  real(8)   y: ECEF 座標 Y
  ! :param(in)  real(8)   z: ECEF 座標 Z
  ! :param(out) real(8) lat: BLH  座標 Beta(Latitude)
  ! :param(out) real(8) lon: BLH  座標 Lambda(Longitude)
  ! :param(out) real(8)  ht: BLH  座標 Height
  subroutine conv_ecef2blh(x, y, z, lat, lon, ht)
    implicit none
    real(DP), intent(in)  :: x, y, z
    real(DP), intent(out) :: lat, lon, ht
    real(DP) :: p, theta, s, c

    p = sqrt(x * x + y * y)
    theta = atan2(z * A, p * B) / PI_180
    s = sin(theta * PI_180)
    c = cos(theta * PI_180)
    lat = atan2(z + ED2 * B * s * s * s, p - E2  * A * c * c * c) &
      & / PI_180
    lon = atan2(y, x) / PI_180
    ht = (p / cos(lat * PI_180)) - f(lat)
  end subroutine conv_ecef2blh

  ! Function for ecef2blh
  !
  ! :param(in) real(8) x
  ! :return    real(8) f
  real(DP) function f(x)
    implicit none
    real(DP), intent(in) :: x
    real(DP) :: s

    s = sin(x * PI_180)
    f = A / sqrt(1.0_DP - E2 * s * s)
  end function f
end program ecef2blh