[OSRS-PROJ] cs2cs and datum shift]

[Duncan Agnew]

A correction to my earlier posting (implicit in Prof. Mugnier's earlier
comment):

If the scale factor in the forward direction is sc, the scale factor
in the inverse should be

     1.e6*(1.0 -  1./(1+(sc/1.e6)))

which means that, for example, a scale factor of 200 (ppm) needs -199.96
for the inverse. The forward/inverse test then does well even for such
larger values of sc.

Duncan Agnew
IGPP/SIO/UCSD

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