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 standard deviation of closing prices 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.
