02 Apr 2026

Introduction to Python

Variables, statements, comments, input, output, and the structure of a simple Python program.

msc semester-i computational-techniques python

Python is an interpreted programming language. It is widely used in computational physics because numerical calculations, plotting, data handling, and symbolic work can be written in a short and readable form.

Basic structure

A Python program is a sequence of statements. Each statement performs one action.

x = 4
y = 5
z = x + y
print(z)

Here x, y, and z are variables. A variable stores a value and gives it a name.

Comments

Comments are ignored by Python. They are used to explain the purpose of the code.

# speed in metre per second
v = 12.5

Good comments explain the physical meaning, not the obvious syntax.

Input and output

The function print() displays output.

temperature = 300
print("Temperature =", temperature, "K")

The function input() reads text from the keyboard. It gives a string, so numerical input must be converted.

radius = float(input("Enter radius: "))
area = 3.14159 * radius**2
print(area)

Indentation

Python uses indentation to mark blocks of code. A block belongs to a function, conditional, or loop.

if x > 0:
    print("positive")

The indented line runs only when the condition is true.

Key points

• Python code is read from top to bottom.
• Variables are created when a value is assigned.
• Use meaningful names such as mass, time, and energy.
• Indentation is part of the syntax.