Trying to understand what's happening

Hello,

I'm trying to understand what's happening here exactly, as I'm not knowing Ruby, and trying to translate it to Swift:

input.each_with_index do |input_scalar, input_index|
                output.each_with_index do |output_scalar, output_index|

                    self.matrix[input_index] ||= []

                    self.matrix[input_index][output_index] ||= 0

                    self.matrix[input_index][output_index] += input_buffer[input_index] * output_buffer[output_index]

                end

            end

What is the ||= for? What exactly is achieved by this fragment in Network.rb?

Thanks for your support!

Best regards,
Hardy

Another question:

def converge_and_bitmask_input(input)
            bitmask(converge_input(input))
        end

This function calculates something, but doesn't return a value - what is the effect here?

[francescoagati]

ruby has return implicit. last expression is always returned.
||= stand for create if not exists