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#+LaTeX_CLASS: beamer
#+LaTeX_CLASS_OPTIONS: [presentation]
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#+LaTeX_CLASS: beamer
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#+LaTeX_HEADER: \usepackage{mathpazo,courier,euler} \usepackage[scaled=.95]{helvet}
#+LaTeX_HEADER: \usepackage{listings}
#+LaTeX_HEADER:\lstset{language=Python, basicstyle=\ttfamily\bfseries,
#+LaTeX_HEADER: commentstyle=\color{red}\itshape, stringstyle=\color{darkgreen},
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#+TITLE: Getting started with functions
#+AUTHOR: FOSSEE
#+EMAIL: info@fossee.in
#+DATE:
#+DESCRIPTION:
#+KEYWORDS:
#+LANGUAGE: en
#+OPTIONS: H:3 num:nil toc:nil \n:nil @:t ::t |:t ^:t -:t f:t *:t <:t
#+OPTIONS: TeX:t LaTeX:nil skip:nil d:nil todo:nil pri:nil tags:not-in-toc
* Outline
- Define functions
- Pass arguments to functions
- Learn about docstrings
- Return values from functions
* Function
- Eliminate code redundancy
- Help in code reuse
- Subroutine
- relatively independent of remaining code
* ~f(x)~ a mathematical function
$f(x) = x^{2}$
: f(1) -> 1
: f(2) -> 4
* Define ~f(x)~ in Python
#+begin_src python
def f(x):
return x*x
#+end_src
- ~def~ - keyword
- ~f~ - function name
- ~x~ - parameter / argument to function ~f~
* Exercise 1
Write a python function named ~cube~ which computes the cube of a given
number ~n~.
- Pause here and try to solve the problem yourself.
* Solution
#+begin_src python
def cube(n):
return n**3
#+end_src
* ~greet~ function
Function ~greet~ which will print ~Hello World!~.
#+begin_src python
def greet():
print "Hello World!"
#+end_src
- Call the function ~greet~
: In []: greet()
: Hello World!
* Exercise 2
Write a python function named ~avg~ which computes the average of
~a~ and ~b~.
- Pause here and try to solve the problem yourself.
* Solution 2
#+begin_src python
def avg(a,b):
return (a + b)/2
#+end_src
- ~a~ and ~b~ are parameters
- ~def f(p1, p2, p3, ... , pn)~
* Docstring
- Documenting/commenting code is a good practice
#+begin_src python
def avg(a,b):
""" avg takes two numbers as input
(a & b), and returns the average
of a and b"""
return (a+b)/2
#+end_src
- Docstring
- written in the line after the ~def~ line.
- Inside triple quote.
- Documentation
: avg?
* Exercise 3
Add docstring to the function f.
* Solution 3
#+begin_src python
def f(x):
"""Accepts a number x as argument and,
returns the square of the number x."""
return x*x
#+end_src
* Exercise 4
Write a python function named ~circle~ which returns the area and
perimeter of a circle given radius ~r~.
* Solution 4
#+begin_src python
def circle(r):
"""returns area and perimeter of a circle given
radius r"""
pi = 3.14
area = pi * r * r
perimeter = 2 * pi * r
return area, perimeter
#+end_src
* ~what~
#+begin_src python
def what( n ):
if n < 0: n = -n
while n > 0:
if n % 2 == 1:
return False
n /= 10
return True
#+end_src
* ~even_digits~
#+begin_src python
def even_digits( n ):
"""returns True if all the digits of number
n is even returns False if all the digits
of number n is not even"""
if n < 0: n = -n
while n > 0:
if n % 2 == 1:
return False
n /= 10
return True
#+end_src
* ~what~
#+begin_src python
def what( n ):
i = 1
while i * i < n:
i += 1
return i * i == n, i
#+end_src
* ~is_perfect_square~
#+begin_src python
def is_perfect_square( n ):
"""returns True and square root of n,
if n is a perfect square, otherwise
returns False and the square root
of the next perfect square"""
i = 1
while i * i < n:
i += 1
return i * i == n, i
#+end_src
* Summary
- Functions in Python
- Passing parameters to a function
- Returning values from a function
- We also did few code reading exercises.
* Thank you!
#+begin_latex
\begin{block}{}
\begin{center}
This spoken tutorial has been produced by the
\textcolor{blue}{FOSSEE} team, which is funded by the
\end{center}
\begin{center}
\textcolor{blue}{National Mission on Education through \\
Information \& Communication Technology \\
MHRD, Govt. of India}.
\end{center}
\end{block}
#+end_latex
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