(PHP 4, PHP 5)



float atan ( float $arg )

Возвращает арктангенс числа arg в радианах. atan() - обратная тригонометрическая функция к tan(), т.е. a==tan(atan(a)) для каждого значения a, входящего в область значений функции atan().

Список параметров


Аргумент функции

Возвращаемые значения

Арктангенс числа arg в радианах.

Смотрите также

  • tan() - Тангенс
  • atanh() - Гиперболический арктангенс
  • asin() - Арксинус
  • acos() - Арккосинус


Arc Tan curve manipulation.

I used this formula to help with increasing and then diminishing return for y given an increasing x for a game.

Ie: Food production (output) is y. Food research is x.

The more research you put into x the more you produce, however after a certain point you get less reward.

 y = atan(x - pi()) + pi()/2;

The + pi()/2 moves it up the y axis so you'd add more if you want it to start higher.

The x - pi() moves it to the right so you'd minus more to move it more.

If you want stretched along the y axis change it to 2 * atan( ...... )

Dunno how useful it is... but it's there.

2003-11-27 20:24:35
to obtain the direction of the line, you are better to use the <? atan2((y2-y1)/(x2-x1)) ?> function, since the regular atan function will only return arguments in the half-plane, ie. if y2-y1 and x2-x1 are negative, atan will give you an angle measurement less than 90 degrees, while it really should be  between 180 and 270
2006-01-11 19:12:28
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.
2014-08-31 02:38:06
arcctg function

function actg($arg){
    return acos($arg/(sqrt(1 + $arg * $arg)));
2016-04-29 23:52:38

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