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Einführung> <gmp_xor
Last updated: Fri, 14 Nov 2008

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Mathematical Functions



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Math
Sanjay Ichalkaranje
11-Oct-2008 11:34
This is the only function I searched that I did not find anywhere on the Internet. This function calculates standard normal cumulative distribution for a particular value. This is NORMSDIST(x) in MS-Excel or OpenOffice.org Calc program.

<?
function normalDist($zScore) {
   
$p = floatval(0.2316419);
   
$b1 = floatval(0.319381530);
   
$b2 = floatval(-0.356563782);
   
$b3 = floatval(1.781477937);
   
$b4 = floatval(-1.821255978);
   
$b5 = floatval(1.330274429);
   
$t = 1/(1 + ($p * floatval($zScore)));
   
$zx = (1/(sqrt(2 * pi())) * (exp(0 - pow($zScore, 2)/2)));

   
$px = 1 - floatval($zx) * (($b1 * $t) + ($b2 * pow($t, 2)) + ($b3 * pow($t, 3)) + ($b4 * pow($t, 4)) + ($b5 * pow($t,5)));
    return
$px;
}
?>

Einführung> <gmp_xor
Last updated: Fri, 14 Nov 2008
 
 
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