[daip] negative feature in IMMOD

[Eric Greisen]

Claire Chandler writes:
 > I'm trying to use IMMOD to make a model source, and have found that for 
 > all opcodes except 'POIN' the model structures inserted into the map are 
 > negative.  I have to specify a negative zero spacing flux in order for the 
 > source to come out positive.
 > 

I have some trouble finding that in the code - I find the reverse.  If
the X increment is positive (or the Y increment negative) then the
code scaled the brightness of the POIN object by the cell size with a
negative sign included.  All other models use BMAJ and BMIN - if one
of those were negative then the source would be negative.  I have
changed the code to use ABS(BMAJ), ABS(BMIN) and the ABS of the
product of the increments in the POINt case.

Eric Greisen