Java 为什么BigDecimal的除法返回0?
我使用Chudnovsky算法计算PI: 代码如下:Java 为什么BigDecimal的除法返回0?,java,Java,我使用Chudnovsky算法计算PI: 代码如下: import java.math.BigDecimal; import java.math.MathContext; import java.util.Scanner; public class main { public static void main(String[] args) { Scanner reader = new Scanner(System.in); int summationU
import java.math.BigDecimal;
import java.math.MathContext;
import java.util.Scanner;
public class main {
public static void main(String[] args) {
Scanner reader = new Scanner(System.in);
int summationUpperLimit;
int precision;
System.out.println("Enter the summation upper limit: ");
summationUpperLimit = reader.nextInt();
System.out.println("Enter the precision: ");
precision = reader.nextInt();
System.out.println(calculatePI(summationUpperLimit, precision));
}
private static int calculateFactorial(int n) {
int factorial = 1;
for (; n > 1; n--) {
factorial = factorial * n;
}
return factorial;
}
private static BigDecimal calculatePI(int summationUpperLimit, int precision) {
BigDecimal reciprocalOfPI = BigDecimal.ZERO;
reciprocalOfPI.setScale(precision - 1, BigDecimal.ROUND_HALF_UP);
for (int k = 0; k <= summationUpperLimit; k++) {
BigDecimal numerator = BigDecimal.valueOf(12 * Math.pow(-1, k) * calculateFactorial(6 * k) * (13591409 + 545140134 * k));
numerator.setScale(precision - 1, BigDecimal.ROUND_HALF_UP);
BigDecimal denominator = BigDecimal.valueOf(calculateFactorial(3 * k) + Math.pow(calculateFactorial(k), 3) * Math.pow(640320, 3 * k + 1.5));
denominator.setScale(precision - 1, BigDecimal.ROUND_HALF_UP);
// The issue is the line below:
reciprocalOfPI = reciprocalOfPI.add(numerator.divide(denominator, BigDecimal.ROUND_HALF_UP));
}
return reciprocalOfPI.pow(-1, MathContext.DECIMAL128);
}
}
在调试模式下,我检查了输出:
numerator = 163096908
denominator = 512384048.99600077
reciprocalOfPI = 0 (this value was taken after the division)
163096908/512384048.99600077不等于0,那么为什么表达式reciprocarofpi=reciprocarofpi.add(分子.除法(分母,BigDecimal.ROUND_-HALF_-UP))代码>设置<代码>往复FPI
为0
我设置比例=精度-1
的理由:
precision=scale+1
因此scale=precision-1
可能是因为
reciprocalOfPI.setScale(precision - 1, BigDecimal.ROUND_HALF_UP);
应该是哪一个
reciprocalOfPI = reciprocalOfPI.setScale(precision - 1, BigDecimal.ROUND_HALF_UP);
BigDecimal是不可变的。它所有的“变异”方法都返回一个新的BigDecimal,而原来的方法保持不变。这可能是由于
reciprocalOfPI.setScale(precision - 1, BigDecimal.ROUND_HALF_UP);
应该是哪一个
reciprocalOfPI = reciprocalOfPI.setScale(precision - 1, BigDecimal.ROUND_HALF_UP);
BigDecimal是不可变的。它所有的“变异”方法都会返回一个新的bigdecime,而原始的bigdecime保持不变。对
倒数运算FPI
、分子
和分母
进行修改似乎必须解决它。哦,是的。我忽略了其他变量上的相同错误。对reciprocalOfPI
、分子
和分母
进行修改似乎必须解决它。哦,是的。我错过了其他变量的相同错误。