Polynomial multiplication Karatsuba

MP.jl

function MP3(p1::Vector{Int64},p2::Vector{Int64})
  if length(p1) == 1 || length(p2) == 1
    return([p1[1]*p2[1]])
  end
  n = length(p1)
  n_div2 = floor(Int64,n/2)

  A = p1[1:n_div2] 
  B = p1[(n_div2+1):(n)] 
  C = p2[1:n_div2]
  D = p2[(n_div2+1):(n)] 

  AC = MP3(A,C)
  BD = MP3(B,D)
  AC_BD = MP3(A+B,C+D)

  MP = Array(Int64,2*n-1)
  for i = 1:2*n-1
    if i <= n_div2
      MP[i] = AC[i]
    elseif i > n_div2 && i < n_div2+n
      i2 = i - n_div2
      aux =0
      if i <= n-1
        aux = AC[i]
      elseif i > n
        aux = BD[i-n]
      end
      MP[i] = aux+(AC_BD[i2] -AC[i2] - BD[i2])
    else
      MP[i] = BD[i-n]
    end
           
  end
  return MP
end