What's the efficient way to multiply two arrays and get sum of multiplied values in Ruby?

Question

What\'s the efficient way to multiply two arrays and get sum of multiply values in Ruby? I have two arrays in Ruby:

array_A = [1, 2, 1, 4, 5, 3, 2, 6, 5, 8, 9]
a         


        

Answer 1

Walking through each element should be a must

(0...array_A.count).inject(0) {|r, i| r + array_A[i]*array_B[i]}