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<?php
namespace Nyholm\EffectiveInterest;
/**
* Newton-Raphsons method to do a numerical analysis to find the effective interest.
*
* {@link https://en.wikipedia.org/wiki/Newton%27s_method}
* @author Tobias Nyholm <[email protected]>
*/
class NewtonRaphson
{
* @var int
private $precision;
* @param int $precision
public function __construct(int $precision = 7)
$this->precision = $precision;
}
* @param callable $fx
* @param callable $fdx
* @param float $guess
* @return float
public function run(callable $fx, callable $fdx, float $guess): float
$newValue = $guess;
$errorLimit = pow(10, -1 * $this->precision);
do {
$previousValue = $newValue;
$newValue = $previousValue - ($fx($previousValue) / $fdx($previousValue));
} while (abs($newValue - $previousValue) > $errorLimit);
return $newValue * 12;
Nyholm /
effective-interest-rate
