I couldn't find mathematical functions to calculate average and standard deviation across all the values in a data series? I used the code below, but the compiler doesn't recognize average() and stdev()

CODE:
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Also, I'm using LinerRegSlope(150) series to determine long-term trends and when the slope exceeds its average+/-standard deviation, i call it a Bullish or Bearish long-term trend.
- If there's an easier way to define long-term trend without a significant lag, pl advise .. moving average cross-over/cross-under (e.g. SMA(100), SMA(200)) don't work well because they have significant lag.

thanks
Kiran

QUOTE:
I used the code below, but the compiler doesn't recognize average() and stdev()

See Pages of the Category Standard Indicators:

* SMA for the average
* StdDev for standard deviation

Are both standard indicators, i.e. are prepackaged. When reviewing code examples, keep in mind that a standard DataSeries like Close - if it's accepted as a parameter by SMA/StdDev - can be substituted with any other DataSeries of your choice.