function [data,gridname]=read_v2r(fname)
%READ_V2R read a FEM output file of .v2r filetype.
%   READ_V2R is part of a suite of OPNML I/O functions  
%   to read specific filetypes pertaining to FEM model  
%   input and output.   These functions allow the user to
%   get these data files into MATLAB without copying the
%   files and removing the header info by hand.
%
%   READ_V2R reads the ascii filetype .v2r, as detailed in 
%   "Data File Standards for the Gulf of Maine Project" from 
%   the Numerical Methods Laboratory at Dartmouth College.
%   There are three columns, the 
%   first of which is the node number.  The second and third   
%   columns are floating point numbers.  The filetype suffix
%   ('.v2r') must be included in the input file name.   
%
%   Input :   If fname is omitted, READ_V2R enables a file browser
%             with which the user can specify the .v2r file.
%
%             Otherwise, fname is the name of the file, relative or 
%             absolute (fullpath), including the '.v2r' suffix; 
%             This input is a string so it must be enclosed in single 
%             quotes. The comment line is discarded.
%
%  Output :   Call READ_V2R as:
%             >> [data,gname]=read_v2r(fname);
%             The domain name will be returned in "gname".
%             The node counter,  amplitudes  of the u and v
%             components of the vector field are returned in "data".
%
%             If READ_V2R cannot locate the file, it exits, returning 
%             a -1 instead of the data matrix.
%
% Call as: [data,gname]=read_v2r(fname);
%
% Written by : Brian O. Blanton
%

if nargin==0 & nargout==0
   disp('Call as: [data,gname]=read_v2r(fname); ')
   return
end

if ~exist('fname')
   [fname,fpath]=uigetfile('*.v2r','Which .v2r ?');
   if fname==0,return,end
else
   fpath=[];
end

% get filetype from tail of fname
ftype=fname(length(fname)-2:length(fname));

% make sure this is an allowed filetype
if ~strcmp(ftype,'v2r')
   error(['READ_V2R cannot read ' ftype ' filetype'])
end

% open fname
[pfid,message]=fopen([fpath fname]);
if pfid==-1
   error([fpath fname,' not found. ',message]);
end

% In all filetypes there is always a gridname and description line
% as lines #1 and #2 of the file.
% read grid name from top of file; header line #1
gridname=fgets(pfid);
gridname=blank(gridname);

% read description line from top of file; header line #2
descline=fgets(pfid);

% read data segment 
data=fscanf(pfid,'%d %f %f',[3 inf])';
fclose(pfid);
%
%        Brian O. Blanton
%        Department of Marine Sciences
%        15-1A Venable Hall
%        CB# 3300
%        Uni. of North Carolina
%        Chapel Hill, NC
%                 27599-3300
%
%        919-962-4466
%        blanton@marine.unc.edu
%