% FUNCNAME   A template for function headers.
%
%    The line above gives a very short summary of the function. Write the 
%    line carefully as it is used by Matlab for special purposes. For example, 
%    the default for the *lookfor* function is to only look at the first 
%    comment line.
%
%    Below the first line follows a description of the function, with 
%    paragraphs separated with empty rows.
%
%    The format described here differs in two aspects from the format used
%    by MathWorks. First, the output and input arguments are described below
%    by a parameter list (instead of a free text), pretty much as normally
%    done in e.g. C programming. Second, reference to variables and 
%    functions are here indicated as * * (instead of using capital letters).
%    For example, "input argument *b* must be a string, which as passed on
%    to the function *some_fun*". This scheme is also used for the ARTS
%    forward model. An exception is the first line of the header where the
%    Matlab style is used. Another difference to the Matlab style is that
%    the function declaration is put after the header part (instead of at 
%    the top).
%
%    The function is first described by giving the format. Optional input
%    arguments are given inside square brackets ([]). The output and input
%    arguments are then listed following the example below. 
%
%    It is good practice to give optional input arguments clear default 
%    values, which should be given in the function header. It is normally
%    better to start the function by setting not given input to the default
%    values, than putting more complicated if statements in the code. 
%    This strategy should also be less likely to give unexpected side-effects
%    if more input arguments are added. Examples on how to set default 
%    values are given inside the function below.
%
%    Notice that the history log is not part of the header, and there should
%    be an empty line before the log.
%
% FORMAT   [a1,a2] = example_heading(b,c[,d,e])
%        
% OUT   a1   A descrition of the variable.
%       a2   A descrition of the variable.
% IN    b    A descrition of the variable. The description can run over 
%            several lines. 
%       c    A descrition of the variable.
% OPT   d    A descrition of the variable. Default is 0.
%       e    A descrition of the variable. Default is [].

% 2002-12-07   Created by Patrick Eriksson 
% 2002-12-09   A big improvement by PE.


function [a1,a2] = example_heading(b,c,d,e)


%= Default values
%
% Here is two ways to set default values to input arguments not
% given in the function call.
%
if nargin < 3
  d = 0;
end
%
if ~exist( 'e', 'var' )
  e = [];
end 


%= Check consistency of input and catch typical mistakes
%
if nargin < 2
  error('At least two input arguments must be specified')
end
%
if ~ischar( b )
  error('Input argument *b* must be a string.');
end
%
if isempty( d )
  error('Input argument *d* cannot be empty.');
end

a1 = d;

a2 = e;