[Proj] Cartesian (geocentric) transformations

[Richard didier]

Hi all,

Using the following :

cs2cs \
+proj=geocent +towgs84=0.0000,0.0000,0.0000 \
+a=6378137.0000 +b=6356752.3141 +units=m +no_defs \
+to \
+proj=geocent 
+towgs84=789.5240,-626.4860,-89.9040,0.6006,76.7946,-10.5788,-32.324100 \
+a=6378388.0000 +b=6356911.9461 +units=m +no_def
<<EOF
3356123.5400 1303218.3090 5247430.6050
3353657.1750 1303862.6620 5249102.0550
EOF

I got :
3353421.83      1304074.31 5248935.61
3350954.73      1304718.57 5250606.19

While I'm expecting :
3353421.02      1304074.55 5248934.99 (not too bad)
3353740.30      1303962.22 5249236.89 (very bad)

any idea ?
-- 
Didier RICHARD, chef de projet "Diffusion des données numériques" 
Institut Geographique National           tel: +33/0 1.43.98.83.23
2/4 Avenue Pasteur                       fax: +33/0 1.43.98.81.71
F-94165 St-Mande Cedex                e-mail: Didier.Richard at ign.fr