How might this be done in TS?

[Steve Gibbons <sg27@xxxxxxxxxxxxxx>]

Metastock has a function called "valuewhen" the syntax is:

valuewhen(Nth, EXPRESSION, DATA ARRAY)

It returns the value of the Data Array when the expression was true on the 
Nth most recent occurrence.

Example: valuewhen(2,average(c,10) = C,rsi(c,20));

would return the value of RSI on the 2nd most recent occurrence of  close 
equal to the 10 bar moving average.

Thanks

Steve