CODEWITHSUNDEEP
phpmath
abr
abr

Reputation: 103

PHP implementation of custom number distribution

I'm looking for a function to generate random numbers in [a,b]

Function must take one argument - seed and return random x є [a,b]. The probability of x = a is the lowest, but is increasing when moving to b. The probability of x = b should be the highest.

As far as I understand what I'm looking for is an implementation of cumulative distribution function, but can't say for sure. So i'll be glad for direct literature. Or maybe there's an in-box php implementation already?

Thanks

Upvotes: 0

Views: 167

Answers (1)

Žan Kusterle
Žan Kusterle

Reputation: 570

First of all, you did not specify what an argument should be. The function below does not use comulative distribution. Incereasing the $n will cause values close to b more likely to be returned.

function almostRandom() {
    $a = 1;
    $b = 10;
    $n = 2.5;

    $random = rand(0, 1000000) / 1000000;

    $positionInInterval = 1 - pow($random, $n);

    $intervalLength = $b - $a;
    $value = $a + $intervalLength * $positionInInterval;

    return $value;
}

Upvotes: 1

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