Here is a Pascal equation that yields y as a function of the
HighLowRange of the data over a number of days.  Can you reverse the
equation to yield the HighLowRange as a function of y ?

Variable: y(0) ;

y = 0 ;

For days = 2 To 100 Begin  

y = y + ( SquareRoot(days) * Log( ( Average(HighLowRange(days), 50) 
	/ Average(HighLowRange(1)[days-1], 50) ) / SquareRoot(days) ) ) ;
			
End ;