# tablepress/3.4/libraries/vendor/PhpSpreadsheet/Calculation/Statistical/Distributions/Exponential.php

TablePress – Tables in WordPress made easy, version 3.4. 55 lines.

- Page: https://pluginprobe.com/plugins/tablepress/3.4/code/libraries/vendor/PhpSpreadsheet/Calculation/Statistical/Distributions/Exponential.php
- Raw: https://pluginprobe.com/plugins/tablepress/3.4/raw/libraries/vendor/PhpSpreadsheet/Calculation/Statistical/Distributions/Exponential.php
- Modified: 2025-08-26T04:06:14+00:00

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```php
<?php

namespace TablePress\PhpOffice\PhpSpreadsheet\Calculation\Statistical\Distributions;

use TablePress\PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Exception;
use TablePress\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 $cumulative Boolean value indicating if we want the cdf (true) or the pdf (false)
	 *                      Or can be an array of values
	 *
	 * @return array<mixed>|float|string If an array of numbers is passed as an argument, then the returned result will also be an array
	 *            with the same dimensions
	 */
	public static function distribution($value, $lambda, $cumulative)
	{
		if (is_array($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);
	}
}

```