这个方法返回其参数商数的反正切。该ATAN2方法返回-pi和PI 较(x,y)点的角度theta之间的数值。
语法
Math.atan2( x, y )
下面是参数的详细信息:
-
x 和%uA0y%uA0: 一个数字.
返回值:
返回一个数弧度的反正切值
Math.atan2( %uB10, -0 ) returns %uB1PI. Math.atan2( %uB10, +0 ) returns %uB10. Math.atan2( %uB10, -x ) returns %uB1PI for x < 0. Math.atan2( %uB10, x ) returns %uB10 for x > 0. Math.atan2( y, %uB10 ) returns -PI/2 for y > 0. Math.atan2( %uB1y, -Infinity ) returns %uB1PI for finite y > 0. Math.atan2( %uB1y, +Infinity ) returns %uB10 for finite y > 0. Math.atan2( %uB1Infinity, +x ) returns %uB1PI/2 for finite x. Math.atan2( %uB1Infinity, -Infinity ) returns %uB13*PI/4. Math.atan2( %uB1Infinity, +Infinity ) returns %uB1PI/4.
例子:
<html> <head> <title>JavaScript Math atan2() Method</title> </head> <body> <script type="text/javascript"> var value = Math.atan2(90,15) document.write("First Test Value : " + value ) var value = Math.atan2(15,90) document.write("<br />Second Test Value : " + value ) var value = Math.atan2(0, -0) document.write("<br />Third Test Value : " + value ) var value = Math.atan2(+Infinity, -Infinity) document.write("<br />Fourth Test Value : " + value ) </script> </body> </html>
这将产生以下结果:
First Test Value : 1.4056476493802698 Second Test Value : 0.16514867741462683 Third Test Value : 3.141592653589793 Fourth Test Value : 2.356194490192345
%uA0