(PECL trader >= 0.2.0)
trader_plus_dm — Plus Directional Movement
$high
, array $low
[, integer $timePeriod
] )
high
高价，浮点数数组。
low
低价，浮点数数组。
timePeriod
Number of period. Valid range from 2 to 100000.
Returns an array with calculated data or false on failure.