5.3 Floating-point numbers

Floating-point numbers in Python are usually written with a decimal point or in scientific notation.

-3.9005

-3.9005

1.1456e-4

0.00011456

f = -9E100
f

-9e+100

type(f)

float

For scientific notation, you may use either "e" or "E", followed by an integer. The integer is the base 10 exponent. -9E100 means – 9 × 10¹⁰⁰.

Exercise 5.13

What does it mean when the integer after "e" or "E" is negative, as in 2.8e-3?

Python cannot express in floating-point the rational numbers that have infinite decimal expressions because of hardware truncation. In general, Python truncates numbers with too many digits.

1/7

0.14285714285714285

0.10101010101010101010101010101010101

0.10101010101010101

The math module contains many functions...