分割后得到一个数字中的所有小数位数 [英] Get all decimal places in a number after division

问题描述

我现在正在使用BigDecimal，它给了我更多的小数，但还不够我所要做的。我需要能够一直到10 ^ 6的数字。这是我目前的代码。

pre $ BigDecimal num = new BigDecimal（103993 / 33102.0）;
pw.println（num.toString（））;

，并输出 3.14159265301190249175533608649857342243194580078125

其中的数字实际上有更多的小数： http://www.wolframalpha.com/输入/？i = 103993％2F33102

解决方案

  103993 / 33102.0 
  

<作为一个双重的部门。其实，下面是：

$ pre $ BigDecimal num = new BigDecimal（103993 / 33102.0）;

等于：

  double d = 103993 / 33102.0; 
 BigDecimal num = new BigDecimal（d）; 
  

改为使用：

  int scale = 100; 
 BigDecimal num1 = new BigDecimal（103993）; 
 BigDecimal num2 = new BigDecimal（33102）; 
 System.out.println（num1.divide（num2，scale，RoundingMode.HALF_UP）.toString（））; 
  

输出：

  3。 9613316415926530119026040722614947737296840070086399613316415926530119026040722614947737 
  

I am currently using the BigDecimal and it is giving me more decimals but not nearly enough for what I am trying to do. I need to be able to get all the way to the 10^6 digit. This is my current code

BigDecimal num = new BigDecimal(103993/33102.0);
    pw.println(num.toString());

and it outputs 3.14159265301190249175533608649857342243194580078125

where the number actually has a lot more decimals: http://www.wolframalpha.com/input/?i=103993%2F33102

解决方案

You are loosing the precision when evaluating this:

103993/33102.0

as a double division. Actually, the following:

BigDecimal num = new BigDecimal(103993/33102.0);

is equivlent to:

double d = 103993/33102.0;
BigDecimal num = new BigDecimal(d);

instead, use:

int scale = 100;
BigDecimal num1 = new BigDecimal(103993);
BigDecimal num2 = new BigDecimal(33102);
System.out.println(num1.divide(num2, scale, RoundingMode.HALF_UP).toString());

OUTPUT:

3.1415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737296840070086399613316415926530119026040722614947737

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