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<?php

/**
 *
 * Function code for the complex ln() function
 *
 * @copyright  Copyright (c) 2013-2018 Mark Baker (https://github.com/MarkBaker/PHPComplex)
 * @license    https://opensource.org/licenses/MIT    MIT
 */
namespace Complex;

/**
 * Returns the natural logarithm of a complex number.
 *
 * @param     Complex|mixed    $complex    Complex number or a numeric value.
 * @return    Complex          The natural logarithm of the complex argument.
 * @throws    Exception        If argument isn't a valid real or complex number.
 * @throws    \InvalidArgumentException  If the real and the imaginary parts are both zero
 */
if (!function_exists(__NAMESPACE__ . '\\ln')) {
    function ln($complex): Complex
    {
        $complex = Complex::validateComplexArgument($complex);

        if (($complex->getReal() == 0.0) && ($complex->getImaginary() == 0.0)) {
            throw new \InvalidArgumentException();
        }

        return new Complex(
            \log(rho($complex)),
            theta($complex),
            $complex->getSuffix()
        );
    }
}