Module: Narray::Convolve

Defined in:
lib/narray/convolve.rb,
lib/narray/convolve/version.rb

Constant Summary collapse

VERSION = 
"0.1.1"

Class Method Summary collapse

Class Method Details

.convolve(n, m, mode = :full) ⇒ Object 



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# File 'lib/narray/convolve.rb', line 9

def convolve(n, m, mode = :full)
  zero_size = m.size - 1
  out_size = zero_size + n.size
  n_end = out_size - 1
  work_size = out_size + zero_size

  out = Numo::DFloat.zeros(out_size)
  work = Numo::DFloat.zeros(work_size)
  work[zero_size..n_end].store(n[true])

  work_size.times do |i|
    w = i + zero_size
    if w < work_size
      mul = work[i..w] * m
      out[i] = mul.sum
    end
  end

  case mode
  when :full # full: (N+M-1)
    ans = out[true]
  when :same # same: [M,N].max
    s = (m.size / 2.0).round - 1
    e = s + n.size
    ans = out[s...e]
  when :valid # valid: [M,N].max - [M,N].min + 1
    s = zero_size
    e = m.size
    ans = out[s..-e]
  end
  ans
end