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<?php |
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|
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namespace TablePress\PhpOffice\PhpSpreadsheet\Calculation\Engineering; |
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|
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use TablePress\PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled; |
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use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Functions; |
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use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError; |
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|
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class ErfC |
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{ |
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use ArrayEnabled; |
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|
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/** |
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* ERFC. |
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* |
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* Returns the complementary ERF function integrated between x and infinity |
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* |
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* Note: In Excel 2007 or earlier, if you input a negative value for the lower bound argument, |
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* the function would return a #NUM! error. However, in Excel 2010, the function algorithm was |
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* improved, so that it can now calculate the function for both positive and negative x values. |
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* PhpSpreadsheet follows Excel 2010 behaviour, and accepts negative arguments. |
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* |
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* Excel Function: |
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* ERFC(x) |
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* |
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* @param mixed $value The float lower bound for integrating ERFC |
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* Or can be an array of values |
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* |
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* @return array<mixed>|float|string If an array of numbers is passed as an argument, then the returned result will also be an array |
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* with the same dimensions |
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*/ |
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public static function ERFC($value) |
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{ |
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if (is_array($value)) { |
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return self::evaluateSingleArgumentArray([self::class, __FUNCTION__], $value); |
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} |
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|
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if (is_numeric($value)) { |
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return self::erfcValue($value); |
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} |
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|
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return ExcelError::VALUE(); |
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} |
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|
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private const ONE_SQRT_PI = 0.564189583547756287; |
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|
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/** |
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* Method to calculate the erfc value. |
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* @param float|int|string $value |
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* @return float|int |
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*/ |
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private static function erfcValue($value) |
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{ |
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$value = (float) $value; |
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if (abs($value) < 2.2) { |
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return 1 - Erf::erfValue($value); |
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} |
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if ($value < 0) { |
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return 2 - self::erfcValue(-$value); |
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} |
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$a = $n = 1; |
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$b = $c = $value; |
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$d = ($value * $value) + 0.5; |
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$q2 = $b / $d; |
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do { |
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$t = $a * $n + $b * $value; |
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$a = $b; |
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$b = $t; |
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$t = $c * $n + $d * $value; |
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$c = $d; |
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$d = $t; |
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$n += 0.5; |
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$q1 = $q2; |
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$q2 = $b / $d; |
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} while ((abs($q1 - $q2) / $q2) > Functions::PRECISION); |
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|
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return self::ONE_SQRT_PI * exp(-$value * $value) * $q2; |
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} |
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} |
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