php/vendor/markbaker/complex/classes/src/functions/cos.php

<?php

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

/**
 * Returns the cosine of a complex number.
 *
 * @param     Complex|mixed    $complex    Complex number or a numeric value.
 * @return    Complex          The cosine of the complex argument.
 * @throws    Exception        If argument isn't a valid real or complex number.
 */
if (!function_exists(__NAMESPACE__ . '\\cos')) {
    function cos($complex): Complex
    {
        $complex = Complex::validateComplexArgument($complex);

        if ($complex->isReal()) {
            return new Complex(\cos($complex->getReal()));
        }

        return conjugate(
            new Complex(
                \cos($complex->getReal()) * \cosh($complex->getImaginary()),
                \sin($complex->getReal()) * \sinh($complex->getImaginary()),
                $complex->getSuffix()
            )
        );
    }
}