(PECL trader >= 0.2.0)
trader_natr — Normalized Average True Range
$high
, array $low
, array $close
[, int $timePeriod
] )
high高价，浮点数数组。
low低价，浮点数数组。
close收盘价，浮点数数组。
timePeriodNumber of period. Valid range from 2 to 100000.
Returns an array with calculated data or false on failure.