使用java BigDecimal完成圆周率π的计算
184-11
Yasumasa Kanada
从左至右：Eugene Salamin，Yasumasa Kanada, David H. Bailey，William Gosper
使用java BigDecimal完成圆周率π的计算
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import java.util.*; import java.math.*; /**
*
Title:π 圆周率的计算
*
Description:使用java BigDecimal完成圆周率(Chudnovsky公式)的计算。可以指定计算精度和计算参数。
*/public class Pi {
private BigDecimal result;
public Pi() { }
public void run(int n, int scale) {
if(System.getProperty(\ System.out.println(\ }
BigDecimal upper = new BigDecimal(426880.0000 * Math.sqrt(10005.0000)); upper = upper.setScale(scale, BigDecimal.ROUND_HALF_EVEN);
if(System.getProperty(\ System.out.println(\ }
BigDecimal downer = BigDecimal.valueOf(0);
for (int i = 0; i <= n; i++) {
BigDecimal d0 = factorial(6 * i).multiply ( new BigDecimal( 545140134 * i + 13591409));
BigDecimal d1 = factorial(i); BigDecimal d2 = pow(d1, 3); BigDecimal d3 = factorial(3 * i);
BigDecimal d4 = pow(-640320, 3 * i); BigDecimal d5 = d2.multiply(d3); BigDecimal d6 = d4.multiply(d5);
BigDecimal d = d0.divide( d6, BigDecimal.ROUND_HALF_EVEN );
downer = downer.add(d);
使用java BigDecimal完成圆周率π的计算
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}
if(System.getProperty(\
System.out.println(\ }
if(System.getProperty(\
System.out.println(\ System.out.println(\ }
result = upper.divide(downer, BigDecimal.ROUND_HALF_EVEN);
if(System.getProperty(\
System.out.println(\ } }
public BigDecimal getResult() {
return result; }
public static BigDecimal pow(double val, int power){ return pow(new BigDecimal(val), power); }
public static BigDecimal pow(BigDecimal val, int power){ BigDecimal value = BigDecimal.valueOf(1); for(int i = 1; i <= power; i ++){ value = value.multiply(val); }
return value; }
public static BigDecimal factorial(int n){
BigDecimal value = BigDecimal.valueOf(1); for(int i = 1; i <=n ; i++){
value = value.multiply(BigDecimal.valueOf(i)); }
return value; }
使用java BigDecimal完成圆周率π的计算
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public static void main(String[] args) { if(args.length < 2){
System.out.println(\\+ \nz-baby.Pi \+ \参数(0-无穷大) 精度(1-4294967296)\
System.out.println(\ System.exit(-1); }
int n = Integer.parseInt(args[0]); int scale = Integer.parseInt(args[1]);
System.out.println(\
System.out.println(\ Pi p = new Pi(); p.run(n, scale);
System.out.println(\ System.out.println(\ } }