[Proj] Problem converting from WGS84 to ROME40

[Frank Warmerdam]

On 9/13/05, Luca Casagrande <luca.casagrande at gmail.com> wrote:
> Hi to all guys!
> I need to convert from WGS84 to ROME40 a point on te Peninsula part of
> Italy; surfing through doc, i compose this line:
> 
> cs2cs -vErs +proj=latlong +datum=WGS84   +to +proj=latlong +ellps=intl
> +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68 \punto
> 
> Punto is:
> 43d07'08.7045"N 12d21'17.6455"E 341,964
> 
> And the ouput of that line is:
> 
> 43d07'08.7045"N 12d21'17.6455"E 341     43d7'6.341"N    12d21'18.369"E
> 295.341
> 
> I know for sure that real coordinates are:  43d7'06.3"N    -0d05'50.00"E
> 292,605 ( the longituide in Roma40, start from Monte Mario wich is
> 012° 27'    08,4" Est)

Luca, 

Your are missing the prime meridian specification.  Your ROME40
should have +pm=rome indicating the prime meridian at rome. 

eg. 
cs2cs +proj=latlong +datum=WGS84 +to +proj=latlong +pm=rome
+ellps=intl +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
12d21'17.6455"E 43d07'08.7045"N
0d5'50.03"W     43d7'6.341"N -45.663

Note that the longitude west of rome is equivelent to a negative 
longtidue east of rome in your expected result.

Best regards,
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