How To Compute Parabolic SAR (Stop and Reverse) in Ruby?

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def parabolic_sar(high_values, low_values, acceleration_factor = 0.02, max_acceleration_factor = 0.2)
  sar = 0
  sar_values = []
  trend = 1
  acceleration = acceleration_factor
  max_high = high_values.max
  min_low = low_values.min

  high_values.each_with_index do |high, i|
    low = low_values[i]

    if i == 0
      sar = low
      sar_values << sar
    else
      prev_sar = sar_values.last

      if trend == 1
        if high > max_high
          max_high = high
          acceleration = [acceleration + acceleration_factor, max_acceleration_factor].min
        end

        sar = prev_sar + acceleration * (max_high - prev_sar)
        
        if low < sar
          sar = max_high
          trend = -1
          acceleration = acceleration_factor
          max_high = high_values[0..i].max
          min_low = low_values[0..i].min
        end
      else
        if low < min_low
          min_low = low
          acceleration = [acceleration + acceleration_factor, max_acceleration_factor].min
        end

        sar = prev_sar + acceleration * (min_low - prev_sar)
        
        if high > sar
          sar = min_low
          trend = 1
          acceleration = acceleration_factor
          max_high = high_values[0..i].max
          min_low = low_values[0..i].min
        end
      end
      
      sar_values << sar
    end
  end

  return sar_values
end

# Example usage
high_values = [10, 12, 14, 16, 18]
low_values = [8, 9, 10, 12, 14]
sar_values = parabolic_sar(high_values, low_values)

puts sar_values