# [OSRS-PROJ] Lambert Conformal Conic 1SP

Gerald I. Evenden gerald.evenden at verizon.net
Sun Feb 9 20:45:48 EST 2003

```> In reference to the rounded-off example computations of EPSG for the
> Jamaica National Grid of 1969, for those seeking to validate
> transformations, try chasing the following decimal points:
>
> Latitude = 17º 55'55".80 N
> Longitude = 76º 56' 37."26 W
> X = 255,966.582 m
> Y = 142,493.511 m.

Not difficult:

Using the script:
proj +proj=lcc +lat_1=18 +lat_0=18 +lon_0=-77 +k_0=1 +x_0=250000
+y_0=150000 +ellps=clrk66 +units=m -f '%.4f'<<EOF
76d56'37.26"W 17d55'55.80"N
EOF

we get:

#Lambert Conformal Conic
#       Conic, Sph&Ell
#       lat_1= and lat_2= or lat_0
# +proj=lcc +lat_1=18 +lat_0=18 +lon_0=-77 +k_0=1 +x_0=250000
+y_0=150000
# +ellps=clrk66 +units=m
#Final Earth figure: ellipsoid
#  Major axis (a): 6378206.4000
#  1/flattening: 294.978698
#  squared eccentricity: 0.006768657997
Longitude: 76d56'37.26"W [ -76.943683333 ]
Latitude:  17d55'55.8"N [ 17.932166667 ]
Easting (x):   255966.5818
Northing (y):  142493.5110
Meridian scale (h)*: 1.00000070  ( 6.964e-05 % error )
Parallel scale (k)*: 1.00000070  ( 6.964e-05 % error )
Areal scale (s):     1.00000139  ( 0.0001393 % error )
Angular distortion (w): 0.000
Meridian/Parallel angle: 90.00000
Convergence*: -0d1'2.65" [ -0.01740281 ]
Max-min (Tissot axis a-b) scale error: 1.00000 1.00000

The scale factors are determined numerically in float and
only used as approximate tests.

Gee, that was easy.  Shall we go for 4 digits?  I'll have
to back off once we get to a total of 15 digits as double only
goes so far.

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