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LiveCode function for converting a UTM location to latitude/longitude
script "UTM To LatLong Library"
/**
Summary: Converts UTM coordindates to lat/long
Parameters:
pZoneNumber: A number between 1 and 60.
pZoneLetter: A-Z, Zones A-M are soutern, N-Z are northern/
pEasting: Number
pNorthing: Number
Description:
put utmToLatlong(30, "U", 655874, 5469610) into tLatLong
-- 49.359238,-0.853344
Returns: Point
*/
function utmToLatLong pZoneNumber, pZoneLetter, pEasting, pNorthing
local tNorthernHemisphere
local tLatitude, tLongitude
local t_a, t_e, t_e1sq, t_k0
local tArc, t_mu, t_ei, t_ca, t_cb, t_cc, t_cd, t_phi1
local t_n0, t_r0, t_fact1, t_a1, t_dd0, t_fact2
local t_t0, t_Q0, t_fact3, t_fact4, t_lof1, t_lof2, t_lof3, t_a2, t_a3
local t_zoneCM
put pZoneLetter is among the chars of "NOPQRSTUVWXYZ" into tNorthernHemisphere
if not tNorthernHemisphere then
put 10000000 - pNorthing into pNorthing
end if
put 6378137 into t_a
put 0.081819191 into t_e
put 0.006739497 into t_e1sq
put 0.9996 into t_k0
put pNorthing / t_k0 into tArc
put tArc / (t_a * (1-t_e^2 / 4.0 - 3 * t_e^4 / 64.0 - 5 * t_e^6 / 256.0)) into t_mu
put (1- (1 - t_e * t_e)^(1 / 2.0)) / (1 + (1 - t_e * t_e)^(1 / 2.0)) into t_ei
put 3 * t_ei / 2 - 27 * t_ei^3 / 32.0 into t_ca
put 21 * t_ei^2 / 16 - 55 * t_ei^4 / 32 into t_cb
put 151 * t_ei^3 / 96 into t_cc
put 1097 * t_ei^4 / 512 into t_cd
put t_mu + t_ca * sin(2 * t_mu) + t_cb * sin(4 * t_mu) + t_cc * sin(6 * t_mu) + t_cd * sin(8 * t_mu) into t_phi1
put t_a / (1 - (t_e * sin(t_phi1))^2)^(1 / 2.0) into t_n0
put t_a * (1 - t_e * t_e) / (1 - (t_e * sin(t_phi1))^2)^(3 / 2.0) into t_r0
put t_n0 * tan(t_phi1) / t_r0 into t_fact1
put 500000 - pEasting into t_a1
put t_a1 / (t_n0 * t_k0) into t_dd0
put t_dd0 * t_dd0 / 2 into t_fact2
put tan(t_phi1)^2 into t_t0
put t_e1sq * cos(t_phi1)^2 into t_Q0
put (5 + 3 * t_t0 + 10 * t_Q0 - 4 * t_Q0 * t_Q0 - 9 * t_e1sq) * t_dd0^4 / 24 into t_fact3
put (61 + 90 * t_t0 + 298 * t_Q0 + 45 * t_t0 * t_t0 - 252 * t_e1sq - 3 * t_Q0 * t_Q0) * t_dd0^6 / 720 into t_fact4
put t_a1 / (t_n0 * t_k0) into t_lof1
put (1 + 2 * t_t0 + t_Q0) * t_dd0^3 / 6.0 into t_lof2
put (5 - 2 * t_Q0 + 28 * t_t0 - 3 * t_Q0^2 + 8 * t_e1sq + 24 * t_t0^2) * t_dd0^5 / 120 into t_lof3
put (t_lof1 - t_lof2 + t_lof3) / cos(t_phi1) into t_a2
put t_a2 * 180 / pi into t_a3
put 180 * (t_phi1 - t_fact1 * (t_fact2 + t_fact3 + t_fact4)) / pi into tLatitude
if not tNorthernHemisphere then
put -tLatitude into tLatitude
end if
if pZoneNumber > 0 then
put 6 * pZoneNumber - 183 into t_zoneCM
else
put 3.0 into t_zoneCM
end if
put t_zoneCM - t_a3 into tLongitude
return tLatitude & "," & tLongitude
end utmToLatLong
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