我正在尝试让 Android 手机计算 Pi 的 n 位小数。为此,我正在使用以下代码:
public class Pi {
private static final BigDecimal TWO = new BigDecimal(2);
private static final BigDecimal FOUR = new BigDecimal(4);
private String nummer;
public void pi(final int SCALE) {
BigDecimal a = ONE;
BigDecimal b = ONE.divide(sqrt(TWO, SCALE), SCALE, ROUND_HALF_UP);
BigDecimal t = new BigDecimal(0.25);
BigDecimal x = ONE;
BigDecimal y;
while (!a.equals(b)) {
y = a;
a = a.add(b).divide(TWO, SCALE, ROUND_HALF_UP);
b = sqrt(b.multiply(y), SCALE);
t = t.subtract(x.multiply(y.subtract(a).multiply(y.subtract(a))));
x = x.multiply(TWO);
}
a.add(b).multiply(a.add(b)).divide(t.multiply(FOUR), SCALE, ROUND_HALF_UP);
number(a);
}
public void number(BigDecimal a) {
//nummer = a.toString().length();
nummer = a.toString();
}
public String returnNum() {
return nummer;
}
public static BigDecimal sqrt(BigDecimal A, final int SCALE) {
BigDecimal x0 = new BigDecimal("0");
BigDecimal x1 = new BigDecimal(Math.sqrt(A.doubleValue()));
while (!x0.equals(x1)) {
x0 = x1;
x1 = A.divide(x0, SCALE, ROUND_HALF_UP);
x1 = x1.add(x0);
x1 = x1.divide(TWO, SCALE, ROUND_HALF_UP);
}
return x1;
}
这在任何计算机上都像一个魅力,但是当我尝试在我的 Android 平板电脑上运行它时,它决定 Pi 是 0.8 左右。为什么会发生这种错误计算,我该如何进行?