SumSince

Moving averages, summation 
SYNTAX  SumSince( condition, array ) 
RETURNS  Array 
FUNCTION  The function calculates running sum of array elements since condition was true. It works like:
or like:
but much faster. 
EXAMPLE  
SEE ALSO  Cum() function , Sum() function , BarsSince() function , ValueWhen() function 
The SumSince function is used in the following formulas in AFL online library:
See updated/extended version online.