java.lang.Math.sqrt()返回作为参数传递给它的double类型值的平方根。如果参数为NaN或负数，则结果为NaN。如果参数为正无穷大，则结果为正无穷大。如果传递的参数为正零或负零，则结果将与参数相同。
用法：
public static double sqrt(double a)
Parameter:
a:the value whose square root is to be returned.
Return:
This method returns the positive square root value of
the argument passed to it.
例子1：显示java.lang.Math.sqrt()方法的用法。
// Java program to demonstrate working
// of java.lang.Math.sqrt() method
import java.lang.Math;
class Gfg {
// driver code
public static void main(String args[])
{
double a = 30;
System.out.println(Math.sqrt(a));
a = 45;
System.out.println(Math.sqrt(a));
a = 60;
System.out.println(Math.sqrt(a));
a = 90;
System.out.println(Math.sqrt(a));
}
}
输出：
5.477225575051661
6.708203932499369
7.745966692414834
9.486832980505138
例子2：当参数为NaN或+ infinity时，显示java.lang.Math.sqrt()方法的用法。
// Java program to demonstrate working
// of java.lang.Math.sqrt() method
import java.lang.Math; // importing java.lang package
public class GFG {
public static void main(String[] args)
{
double positiveInfinity = Double.POSITIVE_INFINITY;
double negativeVal = -5;
double nan = Double.NaN;
double result;
// Here argument is negative,
// output will be NaN
result = Math.sqrt(negativeVal);
System.out.println(result);
// Here argument is positive infinity,
// output will also positive infinity
result = Math.sqrt(positiveInfinity);
System.out.println(result);
// Here argument is NaN, output will be NaN
result = Math.sqrt(nan);
System.out.println(result);
}
}
输出：
NaN
Infinity
NaN
