Module: Muze::Core::Windows

Defined in:
lib/muze/core/windows.rb

Overview

Window function generators for short-time analysis.

Constant Summary collapse

CACHE = 
Muze::Core::BoundedCache.new(max_size: 64)

Class Method Summary collapse

Class Method Details

.blackman(n, periodic: false) ⇒ Numo::SFloat

Parameters:

  • n (Integer)
  • periodic (Boolean) (defaults to: false)

Returns:

  • (Numo::SFloat)

Raises:



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# File 'lib/muze/core/windows.rb', line 33

def blackman(n, periodic: false)
  raise Muze::ParameterError, "window length must be positive" if n <= 0
  return Numo::SFloat[1.0] if n == 1

  build_window(n, periodic:) do |k, denom|
    phase = (2.0 * Math::PI * k) / denom
    0.42 - (0.5 * Math.cos(phase)) + (0.08 * Math.cos(2.0 * phase))
  end
end

.blackman_harris(n, periodic: false) ⇒ Numo::SFloat

Parameters:

  • n (Integer)
  • periodic (Boolean) (defaults to: false)

Returns:

  • (Numo::SFloat)

Raises:



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# File 'lib/muze/core/windows.rb', line 46

def blackman_harris(n, periodic: false)
  raise Muze::ParameterError, "window length must be positive" if n <= 0
  return Numo::SFloat[1.0] if n == 1

  build_window(n, periodic:) do |k, denom|
    phase = (2.0 * Math::PI * k) / denom
    0.35875 - (0.48829 * Math.cos(phase)) + (0.14128 * Math.cos(2.0 * phase)) - (0.01168 * Math.cos(3.0 * phase))
  end
end

.hamming(n, periodic: false) ⇒ Numo::SFloat

Parameters:

  • n (Integer)
  • periodic (Boolean) (defaults to: false)

Returns:

  • (Numo::SFloat)

Raises:



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# File 'lib/muze/core/windows.rb', line 23

def hamming(n, periodic: false)
  raise Muze::ParameterError, "window length must be positive" if n <= 0
  return Numo::SFloat[1.0] if n == 1

  build_window(n, periodic:) { |k, denom| 0.54 - (0.46 * Math.cos((2.0 * Math::PI * k) / denom)) }
end

.hann(n, periodic: false) ⇒ Numo::SFloat

Parameters:

  • n (Integer)
  • periodic (Boolean) (defaults to: false)

Returns:

  • (Numo::SFloat)

Raises:



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# File 'lib/muze/core/windows.rb', line 13

def hann(n, periodic: false)
  raise Muze::ParameterError, "window length must be positive" if n <= 0
  return Numo::SFloat[1.0] if n == 1

  build_window(n, periodic:) { |k, denom| 0.5 * (1.0 - Math.cos((2.0 * Math::PI * k) / denom)) }
end

.kaiser(n, beta: 14.0, periodic: false) ⇒ Numo::SFloat

Parameters:

  • n (Integer)
  • beta (Float) (defaults to: 14.0)
  • periodic (Boolean) (defaults to: false)

Returns:

  • (Numo::SFloat)

Raises:



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# File 'lib/muze/core/windows.rb', line 60

def kaiser(n, beta: 14.0, periodic: false)
  raise Muze::ParameterError, "window length must be positive" if n <= 0
  return Numo::SFloat[1.0] if n == 1

  denominator = bessel_i0(beta)
  build_window(n, periodic:) do |k, denom|
    ratio = ((2.0 * k) / denom) - 1.0
    bessel_i0(beta * Math.sqrt([1.0 - (ratio * ratio), 0.0].max)) / denominator
  end
end

.ones(n) ⇒ Numo::SFloat

Parameters:

  • n (Integer)

Returns:

  • (Numo::SFloat)

Raises:



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# File 'lib/muze/core/windows.rb', line 96

def ones(n)
  raise Muze::ParameterError, "window length must be positive" if n <= 0

  Numo::SFloat.ones(n)
end

.resolve(name, n, periodic: false) ⇒ Numo::SFloat

Parameters:

  • name (Symbol, Array, Numo::NArray, Proc)
  • n (Integer)
  • periodic (Boolean) (defaults to: false)

Returns:

  • (Numo::SFloat)

Raises:



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# File 'lib/muze/core/windows.rb', line 106

def resolve(name, n, periodic: false)
  resolved = case name
             when Numo::NArray then Numo::SFloat.cast(name)
             when Array then Numo::SFloat.cast(name)
             when Proc then Numo::SFloat.cast(name.call(n))
             when Symbol then cached_symbol_window(name, n, periodic:).dup
             else
               raise Muze::ParameterError, "Unsupported window: #{name.inspect}"
             end

  raise Muze::ParameterError, "window must have length #{n}" unless resolved.size == n

  resolved
end

.tukey(n, alpha: 0.5, periodic: false) ⇒ Numo::SFloat

Parameters:

  • n (Integer)
  • alpha (Float) (defaults to: 0.5)
  • periodic (Boolean) (defaults to: false)

Returns:

  • (Numo::SFloat)

Raises:



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# File 'lib/muze/core/windows.rb', line 75

def tukey(n, alpha: 0.5, periodic: false)
  raise Muze::ParameterError, "window length must be positive" if n <= 0
  raise Muze::ParameterError, "alpha must be between 0 and 1" unless alpha.between?(0.0, 1.0)
  return ones(n) if alpha.zero?
  return hann(n, periodic:) if alpha == 1.0
  return Numo::SFloat[1.0] if n == 1

  build_window(n, periodic:) do |k, denom|
    position = k.to_f / denom
    if position < alpha / 2.0
      0.5 * (1.0 + Math.cos(Math::PI * ((2.0 * position / alpha) - 1.0)))
    elsif position <= 1.0 - (alpha / 2.0)
      1.0
    else
      0.5 * (1.0 + Math.cos(Math::PI * ((2.0 * position / alpha) - (2.0 / alpha) + 1.0)))
    end
  end
end