For each date, evaluates a formula and then calculates the standard deviation of values among all symbols on that date.
Example
ReturnDeviation: #StdDev ROC(C, 1)
Calculates the average closing price across all stocks today and stores that value in today's slot for each symbol.
Notes
If the formula result is nan (not a number -- unable to calculate)then that stock is not included in the count that is used in the standard deviation calculation.
