Scientific Computing with Python 3

Booleans

Boolean is a datatype named after George Boole (1815-1864). A Boolean variable can take only two values, True or False. The main use of this type is in logical expressions. Here are some examples:

a = True 
b = 30 > 45   # b gets the value False

Boolean expressions are often used in conjunction with the if statement:

if x > 0:
   print("positive")
else:
   print("nonpositive)

Boolean operators

Boolean operations are performed using the and, or, and not keywords in Python:

True and False # False
False or True # True
(30 > 45) or (27 < 30) # True
not True # False
not (3 > 4) # True

The operators follow some precedence rules (refer to section Executing scripts in Chapter 1, Getting started) which would make the parentheses in the third line and in ...