function indx = gridfn( val, res, vec )
%--------------------------------------------------------------------------
%
% PURPOSE: Return the index to all the values in vec that are 
%          within val+/- res/2.
%
% function indx = gridfn( val, res, vec )
% 
% CHANGE LOG:  Date      Name    Comment
%         (1)  5/2/28    Rob     First
%
%--------------------------------------------------------------------------
%
  indx = find( (vec < val+res/2) & (vec > val-res/2) );
