Introduction to Scientific Computation Using Python

by Arun Prasaad Gunasekaran

Video 2 : Meta Information and Basics

Table of Contents

Benefits of these Videos

All the examples here are chosen carefully so that you all get a broad exposure to a variety of programming tools and useful functions and libraries.

Why Python? - Funny Note

Source: http://xkcd.com/353/

Why Python? - Serious note

Is Python absolutely advantageous?

No! Beacuse no programming language is perfect. Then why to choose Python?,

Bottom line : Python is good, but not undisputed.

Other programming languages that are good : R, Julia, Sage, Mathematica, Maple, Matlab, Fortran, C, C++, IDL, Java, JavaScript, etc,

Different Versions of Python

As of 2019, there are two versions of the Python Language: The Legacy 2.x series and the future 3.x series. Python 3.x came to existence because the founder of Python, Guido van Rossum wanted to add more features to the language. The problem was that adding those features meant dismantling the major framework of Python 2.x and rewrite a significant portion of the language. Consequently, to make sure that the already exisiting programs work well and to make sure the new features get implemented, the old version of python, namely 2.x remained as it is for backward compatibility, while the newer version of python namely 3.x has the new features added to it.

The result of this decision is the exisitence of 2 distinct versions of python with a lot of similarities on the top, with many differences underneath.

Python 2 - Legacy

Python 3 - Future

We are in the transition period wherein we have access to use both the versions of Python. In the future, Python 2 will be obsolete, and in this transition period, almost all the libraries are being converted from Python 2 to Python 3. Infact, new libraries are being made in Python 3 extensively.

Consequently, as of 2019, Python 2.x series is stopping all major releases and releasing only sub releases for maintenance purposes. Other than that, the most active development is focussed on Python 3. The support and maintenance is only for people to transition from python 2.x to 3.x soon.

So, what to look for in any programming language?

This is a (personal) checklist to keep in mind to pick a programing language for scientific computation.

Let’s write our first program

Open up a Text Editor and save a file with the extension .py

Program to ask the name, temperature, and rainfall of a place and print it

"""
Program to ask the name, temperature, and rainfall of a place and print it.
"""

# This is a variable to save the place
place = input("Enter the name of the place:")

# Rainfall variable
rainfall = input("Enter the rainfall recorded today in mm:")

# Temperature variable
temperature = float(input("Enter the temperature recorded today in Celsius:"))

# Print statement
print("In ", place, " today it rained ", rainfall, " mm  and the temperature is", temperature, " degree celsius")

Comments and Docstrings

Comment - Lines that are ignored when the program is run. Used for excluding codes and for including messages.


# This is a single line comment
# Comment begins with a hash # symbol

Docstrings - Document strings. Multi-line comments. But more useful for including help/direction messages that appear when help utilities are called. In libraries, this is used as a documentation/help message for functions and classes.

"""
    This is a Docstring. It starts and ends with 
    triple " or triple ' quotes. Mix and match does not work!
"""

'''
    This is also a DocString
'''

Input Command

Input command - Used for getting input from user to a variable.

n = input('Enter the value for n') # Default string input
n = float(input('Enter the value for n')) # Type casted input