Aroon Up [ARNU]

Summary:
This indicator script helps to determine whether the underlying symbol is trending or in a trading range.

Calculation:
The number of bars since the most recent high in an n-period window.

Range:
0 To 100

Developer:
Tushar S. Chande

Interpretation: 
1. Trending: When the indicator script reaches 70 to 100 the underlying indicator is in an upwards trend.
2. Trading Range: When the indicator script reaches 0 the underlying indicator isn't in an upwards trend. (But it could be in a downwards trend).

	 ' Assign the parameters to script variables.
	_indicatorKey = indicatorKey 
	_periods = periods

	 ' Get the underlying indicator values, indexed by bar index.  
	Define values() As Number = IndicatorValues(_indicatorKey, barIndex, length + _periods)
	 ' Use for the number of bars since the lowest value.
	Define barsFromHighest As Integer
	 ' Use for the highest value in the window.
	Define highest As Number
	 ' Use for the calculated Aroon Up values, indexed by bar index.
	Define results(length - 1) As Number
	 ' Calculate the Aroon Up values for the specified bar range.
	For i As Integer = length - 1 To 0 Step -1
		 ' Calculate the Aroon Up value for the current bar.
		barsFromHighest = _periods
		highest = 0
		For j As Integer = i + _periods To i Step -1
			If (values(j) >= highest) Then
				barsFromHighest = j - i
				highest = values(j)
			End If
		Next
		 ' Assign the Aroon Up value for the current bar.
		results(i) = ((_periods - barsFromHighest) / _periods) * 100
	Next
	Return results