/** * Returns the percent-point function, the inverse of the cdf * * @param float $x The test value * @return float The value that gives a cdf of $x */ public function ppf($x) { return $this->calculator->getPpf($x, $this->lambda, $this->k); }
/** * Returns the percent-point function, the inverse of the cdf * * @param float $x The test value * @param float $sigma The scale parameter * @return float The value that gives a cdf of $x */ public function getPpf($x, $sigma = 1) { $lambda = $this->convertSigmaToLambda($sigma); return $this->wei->getPpf($x, $lambda, 2); }