Maths on whole arrays

Maths on an array works on every value at once, with no loop needed.

• a * 2 doubles every value.
• a + b adds matching positions of two arrays of the same shape.
• np.sqrt(a) and np.round(a, 1) work on every value too.

import numpy as np
a = np.array([1, 2, 3])
b = np.array([10, 20, 30])
print((a * 2).tolist(), (a + b).tolist(), int(a @ b))

[2, 4, 6] [11, 22, 33] 140

Remember: No for loops: let NumPy do the whole array.

Common mistake: Expecting a * b to be matrix multiplication. It multiplies position by position; use @ for matrices.