Class: DSP::Fourier::Radix2

Inherits:
Object
  • Object
show all
Defined in:
lib/dsprb/fourier.rb,
sig/dsprb.rbs

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(size) ⇒ Radix2

Returns a new instance of Radix2.

Parameters:

  • (::Integer)

Raises:

  • (ArgumentError) 


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# File 'lib/dsprb/fourier.rb', line 8

def initialize(size)
  @size = Integer(size)
  raise ArgumentError, "FFT size must be a positive power of two, got #{@size}" unless power_of_two?(@size)

  @stages = build_stages(@size)
  freeze
end

Instance Attribute Details

#size ⇒ ::Integer (readonly)

Returns the value of attribute size.

Returns:

  • (::Integer) 


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# File 'lib/dsprb/fourier.rb', line 6

def size
  @size
end

Instance Method Details

#call(real, imaginary) ⇒ [::Array[::Float], ::Array[::Float]]

Parameters:

  • (::Array[::Float])
  • (::Array[::Float])

Returns:

  • ([::Array[::Float], ::Array[::Float]]) 


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# File 'lib/dsprb/fourier.rb', line 16

def call(real, imaginary)
  assert_size!(real, imaginary)
  permute(real, imaginary)

  span = 2
  while span <= @size
    cosines, sines = @stages[span]
    half = span / 2
    block = 0
    while block < @size
      index = 0
      while index < half
        butterfly(real, imaginary, block + index, half, cosines[index], sines[index])
        index += 1
      end

      block += span
    end

    span <<= 1
  end

  [real, imaginary]
end