diff -r 76fd286276f7 -r fa5c77536e4e functions.org
--- a/functions.org	Mon Sep 13 18:35:56 2010 +0530
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,130 +0,0 @@
-* Functions
-*** Outline
-***** Functions
-******* review of what's been done in solving equations tutorial
-********* def
-********* name
-********* arguments
-********* indented block
-********* calling a function
-******* arguments are local to a function
-******* return values
-******* doc strings - with example.
-******* code reading exercises?
-******* default arguments
-******* keyword arguments
-******* availability library functions
-*** Script
-    Welcome friends. 
-
-    In this tutorial we shall be looking at Functions in Python. We already
-    have looked at the basics of functions in the tutorial on solving
-    equations. We shall first review these basics. Then we shall move on to
-    other details such as doc-strings, default arguments and keyword
-    arguments. 
-    
-    First let's start IPython by typing ipython in the terminal.
-
-    Let's write a simple function that prints a Hello message, upon
-    accepting a name. 
-
-        def welcome(name):
-	    print "Hello", name 
-
-    You would recall that def is a keyword that indicates the function
-    definition. 'welcome' is the name of the function and 'name' is
-    the lone argument to the function. Note that the function is
-    defined within an indented block, just like to any other block. Our
-    function welcome just has one line in it's definition.  
-    
-    We can call our function, as follows -
-        welcome("World")
-
-    (all arguments are local to a function)
-
-    In general functions should be accompanied by documentation on how
-    to use them. Python provides a convenient way of writing this within the
-    function itself, using what are called doc strings. They were mentioned in the
-    tutorial on strings. Let's look at how to write them here. 
-
-    Let us add a simple doc string to our welcome function. 
-
-        def welcome(name):
-	    """ Prints a hello message given a name, 
-	        passed as argument. """
-	    print "Hello", name 
-    
-    Notice that the doc string uses triple quotes. If the doc-string
-    exceeds one line, we can use new line characters in it. 
-    Also, as expected the doc-string is indented as is required
-    for anything within a block. Now that we have written the
-    documentation, how do we access it? IPython provides the question
-    mark feature that we have seen in the previous tutorials. welcome?
-    will display the docstring that we have just written.
-
-    We shall now look at default arguments. 
-    [show slide with examples of functions with default arguments]
-    The split function has been used in two different ways in the
-    given example - one for splitting on spaces and the other for
-    splitting on commas.
-
-    The function split is being called with no arguments and one
-    argument, respectively. In the first case, white space is being
-    used as a default value. Let's now edit our function, welcome, to
-    use default values. (For convenience sake, we have dropped the doc-string)
-
-        def welcome(name="World!"):
-	    print "Hello", name 
-    
-    Now, we call the function 'welcome' without passing any arguments
-    to it. 
-        welcome()
-
-    As you can see the output is "Hello World!". Here "World!" is used as a
-    default argument, when no name argument is passed to 'welcome'. 
-
-    Let's now look at the use of keyword arguments. 
-    [show slide with examples of functions with keyword arguments]
-    We have already looked at functions and keyword arguments in these
-    examples. loc, linewidth, xy, labels are all keywords. 
-
-    Let's now edit our function so that it displays a custom 
-    greeting message as well. 
-
-    def welcome( greet = 'Hello', name = 'World!'):
-        print greet, name
-
-    Let's now see, how we can call our updated 'welcome' function, using
-    keyword arguments. We can call the function in a variety of ways.
-        welcome("Hello", "James")
-	welcome("Hi", name="Guido")
-	welcome(name="Guido", greet="Hello")
-
-    Keyword arguments allow us to call functions by passing arguments
-    in any order and removes the need to remember the order of arguments
-    in the function definition. 
-
-    Let's now write a new function 
-
-    def per_square(n):
-        i = 1
-	while ( i*i < n ):
-	    i += 1
-	return i*i == n, i
-
-    What does this function do? It checks if the given number is a perfect square.
-    If it is, then the function returns True along with the square root of
-    the given number. If the number is not a perfect square it returns
-    False and the square root of the next perfect square.
-
-    Please observe that this function returns 2 values.
-    In Python there is no restriction on the number of values returned by
-    a function. Whenever a function has to return more than one value, the multiple
-    values are packed into one single tuple and that single tuple is returned.
-
-    With this we come to the end of this tutorial on functions. In this tutorial
-    we have learnt about functions in a greater detail. We looked at
-    how to define functions, calling them, default and keyword
-    arguments. 
-
-*** Notes