acos

(PHP 4, PHP 5, PHP 7)

acos反余弦

说明

float acos ( float $arg )

返回 arg 的反余弦值,单位是弧度。acos()cos() 的反函数,它的意思是在 acos() 范围里的每个值都是 a==cos(acos(a))

参数

arg

要处理的参数

返回值

arg 的反余弦弧度。

参见

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User Contributed Notes 2 notes

up
-1
nurlanovic at gmail dot com
5 months ago
With this function you can get the number PI.
This is done like this: acos(-1) === M_PI
up
-24
zoltan dot szentesi at nokia dot com
11 years ago
Wondering what is the use of 'acos' function?

It is essential in games, animations and drawings to determine the location of two objects relating to each other.

To the point: the angle of two vectors is calculated by

           v1X*v2X + v1Y*v2Y
  acos(--------------------------)=angle between two vectors.
               |v1| * |v2|

|v1| and |v2| are the length of the vectors and calculated using Pithagoras-formula: |v1|=sqrt(v1X*v1X + v1Y*v1Y)

This helped me to calculate and share given space for 'n' amount of objects so that they don't overlap.

Enjoy! :-)
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