Taken from MIND LINK! on Fri Mar  3 12:06:06 1995

Fri Mar  3 11:13:28 1995
Letter  : 3660636    From: Ken Hill
Address : khill@HUSKY1.STMARYS.CA
Subject : Long/Lat-UTM Conversion
Bytes   : 3209

To: SARINFO@mindlink.bc.ca (Bob Manson)



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Bob:

I tracked down the bug in the conversion code and am sending along a text
file with the revised basic code and a little explanation on how the
conversion is done. Give it a try.

I also have a slightly more sophisticated (compiled) version which allows
for the UTM to Long/Lat conversion as well. If you're interested I could
send it to for uploading to your BBS. Let me know.

Regards,

Ken Hill
khill@husky1.stmarys.ca




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Equation for Converting Long/Lats to UTM Coordinates
Ken Hill ( khill@husky1.stmarys.ca )
Waverley SAR, Nova Scotia

VARIABLES:

        LG = longitude to be converted
        LT = latitude to be converted

CONSTANTS:

        K0 = .0009996
        B1 = 16216.944156
        C1 = 17.2093715258
        A = 7495.8054646
        E = .00676865799783
        E1 = .00681478594645
        K3 = 309100.43
        K4 = 121.08712
        A1 = 111132.092423

EQUATIONS:

        Z = UTM number = INT[(180-LG)/6]+1
        C = Central Meridian = 183-(6*Z)
        P = .36*ABS(C-LG)
        N = UTM Y coordinate (kilometers)
          =
K0*{A1*LT-B1*SIN(2*LT)+C1*SIN(4*LT)+P2*A*SIN(LT)*COS(LT)/SQR[1-E*SIN2(LT)]}
  E2 = distance from Central Meridian (kilometers)
         =
.001*{P*K3*COS(LT)+P3*K4*COS3(LT)*[1-TAN2(LT)+E1*COS2(LT)]}/SQR[1-E*SIN2(LT)
]

(NOTE:  if the point being converted is west of the Central Meridian, E2 is
subtracted
from 500 km. If the point is east of the CM, E2 is added to 500 km.)


Sample BASIC Program for Conversion:

10 DEFDBL A-Z : REM use double precision math
11 CLS
12 PRINT "LONGS/LATS to UTM Conversion" : PRINT
15 PI = 3.14159265359 : K0 = .0009996 : B1 = 16216.944156 : C1 = 17.2093715258
50 A = 7495.8054646 : E = .00676865799783 : E1 = .00681478594645
80 K3 = 309100.43 : K4 = 121.087180418 : A1 = 111132.092423
130 INPUT "LONGITUDE Degrees (0-180)";LG
132 INPUT "LONGITUDE Minutes (0-60);Q1 : IF Q1 > 60 THEN BEEP : GOTO 132
133 REM Enter seconds as a fraction of a minute
134 Q1 = Q1 * 1/60 : LG = LG + Q1 : PRINT
140 INPUT "LATITUDE Degrees (0-80)";LT
142 INPUT "LATITUDE Minutes (0-60)";Q2 : IF Q2 > 60 THEN BEEP : GOTO 142
144 Q2 = Q2 * 1/60 : LT = LT + Q2
150 Z = INT((186 - LG) / 6) : REM Compute UTM Zone
160 L3 = LT : LT = (LT/360) * (2 * PI) : REM Convert LT into radians
170 C = 183 - 6 * Z : P = .36 * ABS(C - LG)
180 N
=K0*(A1*L3-B1*SIN(2*LT)+C1*SIN(4*LT)+P^2*A*SIN(LT)*COS(LT)/SQR(1-E*SIN(LT)^2
))
190 E2 =
.001*(P*K3*COS(LT)+P^3*K4*COS(LT)^3*(1-TAN(LT)^2+E1*COS(LT)^2))/SQR(1-E*
SIN(LT)^2)
200 IF LG > C THEN E2 = 500 - E2 ELSE E2 = 500 +E2
205 PRINT "Longitude = ";LG;: PRINT " Latitude = ";L3
210 PRINT : PRINT  "UTM = ";E2;N
215 E2 = INT(E2*10+.5): E$ = STR$(E2) : E$ = MID$(E$,3,3) : REM Get 6-digit
grid reference
225 N = INT(N*10+.5): N$ = STR$(N) : N$ = MID$(N$,4,3)
230 PRINT "Six Digits = ";E$;" ";N$
240 PRINT: INPUT "Do you want another run (y/n)";W$
250 IF W$ = "y" or W$ = "Y" then RUN


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