function value = s_is_alpha ( s )

%*****************************************************************************80
%
%% s_is_alpha returns TRUE if the string contains only alphabetic characters.
%
%  Discussion:
%
%    Here, alphabetic characters are 'A' through 'Z' and 'a' through 'z'.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    02 May 2004
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    string S, the string to be checked.
%
%  Output:
%
%    logical VALUE, is TRUE if the string contains only
%    alphabetic characters.
%
  for i = 1 : length ( s )

    if ( ~ ch_is_alpha ( s(i) ) )
      value = false;
      return
    end

  end
 
  value = true;

  return
end
