using G_scan_northing

Steve Dzurenko steve at ocean.oce.uri.EDU
Mon Apr 24 08:00:00 EDT 1995

Hi Bill,

I figured out what was going on shortly after I mailed the list.

G_scan* does not convert from one projection to another.  It 
simply converts from ascii to double, sort of like atof, but
with a few extras.  The projection field has nothing to do
with any projection conversions, it just tells G_scan how it
is going to parse the ascii coordinate.  For PROJECTION_LL,
G_scan* converts a string of the form ddd:mm:ss.ssW to a double
of the form -dd.ddddd.  

I figured this out by looking through m.ll2u.  I noticed that
it called CC_ll2u.  I was unfamiliar with that library function.
By looking at the Gmakefiles, I found that there is a library
COORCNVLIB which is not documented in the GRASS Programmers 
Manual.  By a good bit of trial and error, I got CC_ll2u to 
do the ll to utm conversions that I wanted.  One problem, before,
calling CC_ll2u, you must make calls to 


I guess CC_u2ll_spheroid_parameters() sets up something behind
the scenes, because CC_ll2u will not work if that call is not
made first.  No one told me that one!  I love being a 
detective!  Anyway, thanks.


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