Thomas Demark Indicator calculation

The DeMarker indicator is an attempt to overcome the shortcomings of classical overbought / oversold indicators. In Forex The DeMarker Indicator identifies potential price bottoms and tops. It accomplishes this by making price comparisons from one bar to the next and measuring the level of price demand

here is the formula

highm = IIF( H > Ref( H, -1 ), H - Ref( H, - 1), 0 );
lowm = IIF( L < Ref( L, -1 ), Ref( L, - 1 ) - L, 0 );

Tom D = 100 * Sum( highm, 13 )/( Sum( lowm, 13 ) + Sum( highm, 13 ) );