[Proj] Numerical Precision in Proj, WKT, and everywhere

Jean-Claude REPETTO jrepetto at free.fr
Tue Apr 6 07:36:53 EST 2010

Craig Bruce wrote :
> There's also a problem with rational fractions, like 1/60, as I showed
> in the WMS example.  You can easily write x = 1/60.0 in a program get a
> fully precise value for whatever representation you are using, but you
> can't put this expression on the proj command line (AFAIK).

Hello Craig,

I think you are wrong, PROJ.4 accepts minutes (and probably seconds) in 
projection definitions.

This definition :
# NAD27 / Cuba Sur
<2086> +proj=lcc +lat_1=20.71666666666667 +lat_0=20.71666666666667 
+lon_0=-76.83333333333333 +k_0=0.99994848 +x_0=500000 +y_0=229126.939 
+ellps=clrk66 +datum=NAD27 +units=m +no_defs  <>

had rather be written :
<2086> +proj=lcc +lat_1=20d43 +lat_0=20d43 +lon_0=-76d50 +k_0=0.99994848 
+x_0=500000 +y_0=229126.939 +ellps=clrk66 +datum=NAD27 +units=m +no_defs <>

and it works :

$ proj +proj=lcc +lat_1=20d43 +lat_0=20d43 +lon_0=-76d50 +k_0=0.99994848 
+x_0=500000 +y_0=229126.939 +ellps=clrk66 +datum=NAD27 +units=m +no_defs
-76 20
587209.13	150016.01

$ proj +proj=lcc +lat_1=20.71666666666667 +lat_0=20.71666666666667 
+lon_0=-76.83333333333333 +k_0=0.99994848 +x_0=500000 +y_0=229126.939 
+ellps=clrk66 +datum=NAD27 +units=m +no_defs
-76 20
587209.13	150016.01


More information about the Proj mailing list