atan

    (PHP 4, PHP 5, PHP 7, PHP 8)

    atan — Arc tangent

    Опис

    atan(float $num): float

    Returns the arc tangent of num in radians. atan() is the inverse function of tan(), which means that $num == tan(atan($num)) for every value of num that is in the domain of atan().

    Параметри

    num

    The argument to process

    Значення, що повертаються

    The arc tangent of num in radians.

    Прогляньте також

    Found A Problem?

    Learn How To Improve This Page • Submit a Pull Request • Report a Bug
    ＋add a note

    User Contributed Notes 1 note

    up
    9
    Anonymous
    10 years ago
    Contrary to the current description, it should hold y == tan(atan(y)) for ALL y.
    However, x == atan(tan(x)) only holds for those x which are in the range of atan, which are those x with -pi/2 < x < pi/2.

    Of course, those equalities are limited by precision. On my machine
    tan(atan(1000)) returns 1000.0000000001.
    atan(tan(0)) returns 0 (correct).
    atan(tan(M_PI)) returns -1.2246467991474E-16 instead of 0.
    ＋add a note
    To Top