Multiply each item in an array by each item in another array

Question

In Ruby, how can one multiply every element in one array by every element in another array, such that:

a = [1,2,3]

b = [4,5,6]

c = a*b = [4,5,6,8,10,12,12,15,18]

Answer 1

For a nice abstraction, can get cartesian product using product:

a.product(b).map { |aa, bb| aa * bb }