trader_var

(PECL trader >= 0.2.0)

trader_var — Variance

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trader_var ( array $real [, int $timePeriod [, float $nbDev ]] ) : array

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real: ��顣
timePeriod: Number of period. Valid range from 2 to 100000.
nbDev

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Returns an array with calculated data or false on failure.