PHP实现简单线性回归之数学库的重要性

 
<?php  
// Copyright 2003, Paul Meagher  
// Distributed under GPL    
class SimpleLinearRegression {  
    
  var $RPath  = "/usr/local/bin/R";  // Your path here 
  function getStudentProb($T, $df) {     
    $Probability = 0.0;    
    $cmd = "echo 'dt($T, $df)' | $this->RPath --slave";  
    $result = shell_exec($cmd);     
    list($LineNumber, $Probability) = explode(" ", trim($result));  
    return $Probability; 
  } 
  function getInverseStudentProb($alpha, $df) {   
    $InverseProbability = 0.0;  
    $cmd = "echo 'qt($alpha, $df)' | $this->RPath --slave";  
    $result = shell_exec($cmd);   
    list($LineNumber, $InverseProbability) = explode(" ", trim($result));  
    return $InverseProbability; 
  } 
} 
?>

 
<?php  
// BurnoutStudy.php 
// Copyright 2003, Paul Meagher  
// Distributed under GPL    
include "SimpleLinearRegression.php";  
// Load data from burnout study  
$Concentration   = array(20,60,38,88,79,87,  
                         68,12,35,70,80,92,  
                         77,86,83,79,75,81,  
                         75,77,77,77,17,85,96);   
                           
$ExhaustionIndex = array(100,525,300,980,310,900,  
                         410,296,120,501,920,810,  
                         506,493,892,527,600,855,  
                         709,791,718,684,141,400,970);   
                           
$slr = new SimpleLinearRegression($Concentration, $ExhaustionIndex);   
$YInt      = sprintf($slr->format, $slr->YInt); 
$Slope     = sprintf($slr->format, $slr->Slope);     
$SlopeTVal = sprintf($slr->format, $slr->SlopeTVal);     
$SlopeProb = sprintf("%01.6f", $slr->SlopeProb);     
?> 
<table border='1' cellpadding='5'> 
  <tr> 
    <th align='right'>Equation:</th> 
    <td></td> 
  </tr> 
  <tr> 
    <th align='right'>T:</th> 
    <td></td> 
  </tr> 
  <tr> 
    <th align='right'>Prob > T:</th> 
    <td><td> 
  </tr> 
</table>