
The subinxxcsv program changes the size of grids by adding or subtracting
a number of cells from any grid edge. 
It also allows exchanging certain grid corners and cell widths.      
  
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I suggest running the example/tests in this order:

 sh ./Subinxxcsv_example1

 sh ./Subinxxcsv_example2

 sh ./Subinxxcsv_fakestack


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Comments: 

In the trivial use-cases, it may be that you have just over-estimated or 
under-estimated the extent of grid that you need to cover your survey.

But in the not-so-trivial use-cases, you may be trying to use 2d programs to
process 3d surveys. An example of this idea is to employ 2d migration in the
inline grid direction followed by 2d migration in the crossline grid direction
(of course 2d by 2d migration is not usually as good as 3d migration). 
Without knowing the full behavior of any 2d migration program, there are still
several ways that you might use this program:

  1. Make extra dead cells to pad both the inline and crossline directions. 
     (You want to prevent 2d migration operators from reaching backwards or
      forwards and using live data from cdps which are on different inlines 
      or crosslines). 

  2. You may wish to flip the grid so that inline now becomes crossline. 
     This may be necessary to get transposed cdp numbers which you can use in 
     the second cdp sort and second 2d migration. 

Of course, for 2d by 2d migrations, just getting reasonable cdp numbers in the
input traces is not sufficient. You also have to worry about velocity fields,
which are a more difficult problem.                  
