Java Math.PI的价值有多精确？

Question

我能获得PI的第N位数的最大N是多少？

Answer 1

public static final double PI = 3.141592653589793d

所以 N = 16

这就是API在这里所说的:http://docs.oracle.com/javase/6/docs/api/constant-values.html#java.lang.Math.PI

但确实Math.class的源代码说:

public static final double PI = 3.14159265358979323846;

和这里 N = 21

无论如何 - 这有点奇怪;)

Answer 2

这是源代码中写的:

/**
 * The {@code double} value that is closer than any other to
 * <i>pi</i>, the ratio of the circumference of a circle to its
 * diameter.
 */
public static final double PI = 3.14159265358979323846;