atan() 反正切

名称：atan()

例子：

	float a = PI/3; float t = tan(a); float at = atan(t); // Prints "1.0471976 : 1.7320509 : 1.0471976" println(a + " : " + t + " : " + at); float a = PI + PI/3.0; float t = tan(a); float at = atan(t); // Prints "4.1887903 : 1.7320513 : 1.0471977" println(a + " : " + t + " : " + at);

float a = PI/3;
float t = tan(a);
float at = atan(t);
// Prints "1.0471976 : 1.7320509 : 1.0471976"
println(a + " : " + t + " : " +  at);

float a = PI + PI/3.0;
float t = tan(a);
float at = atan(t);
// Prints "4.1887903 : 1.7320513 : 1.0471977"
println(a + " : " + t + " : " +  at);

描述：

tan（）的倒数，返回反正切值。此函数需要-Infinity到Infinity（独占）范围内的值，并将值返回到-PI / 2到PI / 2。

语法：

atan(value)

参数：

value	float: -Infinity to Infinity (exclusive) 无穷小到无穷大（唯一）

返回：float