Previous Value of Function [Prev]

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The Previous Value of Function function returns the value of this function for the previous bar. Parameters ------------------ Period          The number of bars of data to include in the calculation, not including the current day.                     For example, a period of 1 returns the value from the previous bar.                     This value will almost always be 1. Function Value ------------------------ This function returns the previous value of the function it is included in. If the previous value is not defined, this function returns 0. It is primarily used in functions which add a new value to the previous value of the function. For example, an exponential moving average adds a percentage of the new value to a percentage of the previous value of the function. EMA = (Current Value * Percentage) + (Previous EMA * (100 - Percentage)) Periods greater than one are typically not used, but can be used for creating interesting indicators. For example, adding a current value to the previous value from 255 days ago (the typical number of trading days in a year) can create an annual indicator which could be used to detect intrayear trends. Since the Previous Value function can only be used within other functions, it is only available from within the formula editor.