54 lines
2.1 KiB
PHP
54 lines
2.1 KiB
PHP
<?php
|
|
|
|
namespace PhpOffice\PhpSpreadsheet\Calculation\Statistical\Distributions;
|
|
|
|
use PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
|
|
use PhpOffice\PhpSpreadsheet\Calculation\Exception;
|
|
use PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
|
|
|
|
class Exponential
|
|
{
|
|
use ArrayEnabled;
|
|
|
|
/**
|
|
* EXPONDIST.
|
|
*
|
|
* Returns the exponential distribution. Use EXPONDIST to model the time between events,
|
|
* such as how long an automated bank teller takes to deliver cash. For example, you can
|
|
* use EXPONDIST to determine the probability that the process takes at most 1 minute.
|
|
*
|
|
* @param mixed $value Float value for which we want the probability
|
|
* Or can be an array of values
|
|
* @param mixed $lambda The parameter value as a float
|
|
* Or can be an array of values
|
|
* @param mixed $cumulative Boolean value indicating if we want the cdf (true) or the pdf (false)
|
|
* Or can be an array of values
|
|
*
|
|
* @return array|float|string If an array of numbers is passed as an argument, then the returned result will also be an array
|
|
* with the same dimensions
|
|
*/
|
|
public static function distribution(mixed $value, mixed $lambda, mixed $cumulative): array|string|float
|
|
{
|
|
if (is_array($value) || is_array($lambda) || is_array($cumulative)) {
|
|
return self::evaluateArrayArguments([self::class, __FUNCTION__], $value, $lambda, $cumulative);
|
|
}
|
|
|
|
try {
|
|
$value = DistributionValidations::validateFloat($value);
|
|
$lambda = DistributionValidations::validateFloat($lambda);
|
|
$cumulative = DistributionValidations::validateBool($cumulative);
|
|
} catch (Exception $e) {
|
|
return $e->getMessage();
|
|
}
|
|
|
|
if (($value < 0) || ($lambda < 0)) {
|
|
return ExcelError::NAN();
|
|
}
|
|
|
|
if ($cumulative === true) {
|
|
return 1 - exp(0 - $value * $lambda);
|
|
}
|
|
|
|
return $lambda * exp(0 - $value * $lambda);
|
|
}
|
|
}
|