<?php

namespace TablePress\PhpOffice\PhpSpreadsheet\Calculation\Engineering;

use TablePress\PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Functions;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;

class ErfC
{
	use ArrayEnabled;

	/**
	 * ERFC.
	 *
	 *    Returns the complementary ERF function integrated between x and infinity
	 *
	 *    Note: In Excel 2007 or earlier, if you input a negative value for the lower bound argument,
	 *        the function would return a #NUM! error. However, in Excel 2010, the function algorithm was
	 *        improved, so that it can now calculate the function for both positive and negative x values.
	 *            PhpSpreadsheet follows Excel 2010 behaviour, and accepts nagative arguments.
	 *
	 *    Excel Function:
	 *        ERFC(x)
	 *
	 * @param mixed $value The float lower bound for integrating ERFC
	 *                      Or can be an array of values
	 *
	 * @return array|float|string
	 *         If an array of numbers is passed as an argument, then the returned result will also be an array
	 *            with the same dimensions
	 */
	public static function ERFC($value)
	{
		if (is_array($value)) {
			return self::evaluateSingleArgumentArray([self::class, __FUNCTION__], $value);
		}

		if (is_numeric($value)) {
			return self::erfcValue($value);
		}

		return ExcelError::VALUE();
	}

	private const ONE_SQRT_PI = 0.564189583547756287;

	/**
	 * Method to calculate the erfc value.
	 *
	 * @param float|int|string $value
	 *
	 * @return float
	 */
	private static function erfcValue($value)
	{
		$value = (float) $value;
		if (abs($value) < 2.2) {
			return 1 - Erf::erfValue($value);
		}
		if ($value < 0) {
			return 2 - self::erfcValue(-$value);
		}
		$a = $n = 1;
		$b = $c = $value;
		$d = ($value * $value) + 0.5;
		$q2 = $b / $d;
		do {
			$t = $a * $n + $b * $value;
			$a = $b;
			$b = $t;
			$t = $c * $n + $d * $value;
			$c = $d;
			$d = $t;
			$n += 0.5;
			$q1 = $q2;
			$q2 = $b / $d;
		} while ((abs($q1 - $q2) / $q2) > Functions::PRECISION);

		return self::ONE_SQRT_PI * exp(-$value * $value) * $q2;
	}
}
