This is a BIG request for anybody who can develop a DLL to support this feature. If it's possible to find a good implementation for a generic recursive function with a format like this one: - f:= P1*PrType + P2*PrType[1] + P3*PrType[2] + P4*PrType[3] + P5*PrType[4] +A*f[1] +B*f[2] +C*f[3] +D*f[4]; (where f[1],f[2],f[3] and f[4] are references to the function itself 1,2,3 and 4 bars ago repectively. "PrType" is a selection of Std. Price Types OHLC,MP(),Typ() or the output of an external Indicator, refenced 1,2,3 and 4 bars ago. P1,P2,P3,P4,P5,A,B,C,D are constant coeficients that can be entered by the user in the function call parameters list; each one can be Zero as well.) In this case, pretty much any kind of filter can be implemented. To cover even a greater range, maybe up to 6 backward references can be considered. I hope to hear good news on this one. Guara

This sounds more like a lookback function than recursion for two reasons: One, Recursion, i think, should call itself back exactly once per instance. Two, your function won't be defined once u run out of bars to look back at. Here I think you want to maintain history, say in an array. Try solving the problem for the 1st bar, then the second, and see where that gets u. Karl