The scope of a variable is the part of a program that can see that variable.

a = 5
def adjust(b):
	sum = a + b
    return sum
adjust(10)   # what will be the outcome?

• “a” is the global variable => visible everywhere
• “b” and “sum” are local variables => visible only inside the function

Inside a function we can access methods of global variables:

a = []
def add():
    a.append(5)   # modify global `a`
add()
a       # [5]

If we have time

(1) How would you explain the following:

1 + 2 == 3           # returns True (makes sense!)
0.1 + 0.2 == 0.3     # returns False -- be aware of this when you use conditionals
abs(0.1+0.2 - 0.3) < 1.e-8     # compare floats for almost equality
import numpy as np
np.isclose(0.1+0.2, 0.3, atol=1e-8)

(2) More challening: write a code to solve x^3+4x^2-10=0 with a bisection method in the interval [1.3, 1.4] with tolerance 1e-8.