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The atan() function returns the arctangent of a number as a numeric value between -PI/2 and PI/2 radians.
atan()函数的作用是:返回一个指定数值参数的反正切值。
The atan2() function returns the angle theta of an (x,y) point as a numeric value between -PI and PI radians.
atan2()函数的作用是:返回两个指定数值参数的反正切值。
atan(x) atan2(x,y) |
Parameter参数 | Description描述 |
---|---|
x | Required. A number 必要参数。指定一个数值参数 |
y | Required. A number 必要参数。指定一个数值参数 |
The following example returns the arctangent of different numbers with the atan() function:
下面的案例将通过atan()返回不同数值参数所对应的反正切值:
<?php echo(atan(0.50) . "<br />"); echo(atan(-0.50) . "<br />"); echo(atan(5) . "<br />"); echo(atan(10) . "<br />"); echo(atan(-5) . "<br />"); echo(atan(-10)) ?> |
The output of the code above will be:
上述代码将输出下面的结果:
0.463647609001 -0.463647609001 1.37340076695 1.4711276743 -1.37340076695 -1.4711276743 |
The following example returns the angle theta of different (x,y) points with the atan2() function:
下面的案例将通过atan2()返回两个参数的反正切值:
<?php echo(atan2(0.50,0.50) . "<br />"); echo(atan2(-0.50,-0.50) . "<br />"); echo(atan2(5,5) . "<br />"); echo(atan2(10,20) . "<br />"); echo(atan2(-5,-5) . "<br />"); echo(atan2(-10,10)) ?> |
The output of the code above will be:
上述代码将输出下面的结果:
0.785398163397 -2.35619449019 0.785398163397 0.463647609001 -2.35619449019 -0.785398163397 |