[daip] FLATN

[Joseph Lazio]

Hi,


Somebody asked about DOWEIGHT in FLATN.  In staring at both the help
file and the code, it's become considerably less obvious what this
adverb does.  In FLATN.FOR 

            CALL OGET (IN(LFIELD), 'DOWEIGHT', TYPE, DIM, RFACT, CDUMMY,
     *         IRET)
	    [...]
            RFACT = RFACT * 3600.0

That would seem to convert RFACT from degrees into arcseconds, yet the 
HELP file indicates that DOWEIGHT should be given in arcseconds.
Moreover, later in the code

                           ZREF = SIN (YREF) * SIN (DECREF) + COS (YREF)
     *                        * COS (DECREF) * COS (XREF - RAREF)
                           ANGLE = ACOS (ZREF) * RAD2DG
                           WT = WT * MAX (0.0001D0, 1.0D0-ANGLE*RFACT)

ANGLE would appear to be the distance from the map center as measured
in degrees.  In addition to the fact that the units of ANGLE*RFACT
don't appear to make sense, 1-ANGLE*RFACT would seem to be negative
for most naive choices of RFACT.

What are we missing?

-- Joe

-- 
T. Joseph W. Lazio, Ph.D.        voice: +1 202 404 6329
Remote Sensing Division          fax:   +1 202 404 8894
Naval Research Lab, Code 7213    Joseph.Lazio at nrl.navy.mil
Washington, DC 20375-5351 USA    http://rsd-www.nrl.navy.mil/7213/lazio/