(PECL trader >= 0.2.0)
trader_var — Variance
$real
, int $timePeriod
= ?, float $nbDev
= ?): array
real
浮點(diǎn)數(shù)數(shù)組。
timePeriod
Number of period. Valid range from 2 to 100000.
nbDev
Returns an array with calculated data or false on failure.