Parse poisson function in javascript to php : <p>I have the next code in javascript:</p>

<pre><code>var exponential = 2.71828182845904523536028747135266249775724709369995957496696762772407663035354759457138217852516642742746;


var numerator, denominator;

function fact(x) {
if(x==0) {
    return 1;
}
return x * fact(x-1);
}



function poisson(k, landa) {
    exponentialPower = Math.pow(exponential, -landa); // negative power k
    landaPowerK = Math.pow(landa, k); // Landa elevated k
    numerator = exponentialPower * landaPowerK;
    denominator = fact(k); // factorial of k.

    return (numerator / denominator);
}
</code></pre>

<p>I need parse to php but i don't know how...</p>

<p>Can somebody help me?</p>
