NAME: readbat
PURPOSE: reading the bathymetry ASCII file of OPA
CATEGORY: for OPA
CALLING SEQUENCE: bat=readbat(filename)
INPUTS:
filename: a string containing the filename,
KEYWORD PARAMETERS:
/ZERO: to put 0 on land instead of negatives values for the islands.
OUTPUTS: a 2d array
COMMON BLOCKS:no
SIDE EFFECTS:
RESTRICTIONS:
EXAMPLE: