[ferret_users] reading BIG ascii files

[Leticia Cotrim da Cunha <lcotrim@xxxxxxxxxxxxx>]

Hello,

I tried to open big ASCII files organised in columns like this:

lon               lat           NPP
-179.917   89.917   -9999.
-179.750   89.917   -9999.
-179.583   89.917   -9999.
etc

The file has 1542035 lines. 
The format of the ASCII data is F10.3
I wanted to use columns 1 and 2 (lon and lat) to define a grid for NPP.
Longitude (col1) goes from -179.917 to 179.917 at an interval of 0.167 (2160 points).
Latitude (col2) goes from 89.917 to -89.917 at an interval of 0.167 (1080 points).
The files were extracted from 2160x1080 *.hdf files using SEADAS.

I tried to follow the instructions at Ferret documentation, but it did not work (are the files too big?) or I did not understand it (most probable).
Any hints? Thanks a lot for your help!
Best regards
Leticia