trader_linearreg_slope

// If you don't have the php_trader library or needs more than 3 precision digits,// you can use this function:public static function linearreg_slope( $valuesIn, $period ){  $valuesOut = array();    $startIdx = 0;  $endIdx = count($valuesIn) - 1;    $sumX = $period * ( $period - 1 ) * 0.5;  $sumXSqr = $period * ( $period - 1 ) * ( 2 * $period - 1 ) / 6;  $divisor = $sumX * $sumX - $period * $sumXSqr;    for ( $today = $startIdx, $outIdx = 0; $today <= $endIdx; $today++, $outIdx++ )  {    $sumXY = 0;    $sumY = 0;    if ( $today >= $period - 1 ) {      for( $aux = $period; $aux-- != 0; )      {        $sumY += $tempValue = $valuesIn[$today - $aux];        $sumXY += (double)$aux * $tempValue;      }      $valuesOut[$outIdx] = ( $period * $sumXY - $sumX * $sumY) / $divisor;    }  }    return $valuesOut;}

Default value of precision in trader library is 3, but can be increased easily with something like this:ini_set( 'trader.real_precision', '6' );