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subroutine da_lc_cone(truelat1, truelat2, cone) 2,2
!------------------------------------------------------------------------
! Purpose: compute the cone factor of a Lambert Conformal projection
!------------------------------------------------------------------------
implicit none
real, intent(in) :: truelat1 ! (-90 -> 90 degrees N)
real, intent(in) :: truelat2 ! " " " " "
real, intent(out) :: cone
if (trace_use_dull) call da_trace_entry
("da_lc_cone")
! First, see if this is a secant or tangent projection. For tangent
! projections, truelat1 = truelat2 and the cone is tangent to the
! Earth's surface at this latitude. For secant projections, the cone
! intersects the Earth's surface at each of the distinctly different
! latitudes
if (abs(truelat1-truelat2) > 0.1) then
cone = alog10(cos(truelat1*rad_per_deg)) - &
alog10(cos(truelat2*rad_per_deg))
cone = cone /(alog10(tan((45.0 - abs(truelat1)/2.0) * rad_per_deg)) - &
alog10(tan((45.0 - abs(truelat2)/2.0) * rad_per_deg)))
else
cone = sin(abs(truelat1)*rad_per_deg)
end if
if (trace_use_dull) call da_trace_exit("da_lc_cone")
end subroutine da_lc_cone