% Purpose
%    writes out the global attribute value.
%
% Synopsis
%    mexeps('putattval',attname, attval)
%
% Description
%    It writes out the global attribute to current data file.
%
% Examples
%    Write a character string and a read number attribute.
%
%      attname1 = 'Comment';
%      attval1  = 'This is an example data file';
%      mexeps('putattval',attname1, attval1);
%
%      attname2 = 'new_value';
%      attval2 = 123.45;
%      mexeps('putattval',attname2,attval2);
%
% See Also
%    getattnum, attname, getattval, delatt
%