[英]How to get decimal to n places precision in C# program for Pi
With reg to this question Pi in C# 注册到C#中的Pi#
I coded the below code and gives a output with last 6 digits as 0. So I want to improve the program by converting everything to decimal. 我编写了下面的代码并给出了最后6位数为0的输出。所以我想通过将所有内容转换为十进制来改进程序。 I have never used decimal in C# instead of a double before and I am only comfortable with double in my regular use.
我从来没有在C#中使用过十进制而不是之前的双倍,而我在常规使用中只能使用double。
So please help me with decimal conversion, i tried to replace all double to decimal at start and it didnt turn good :(. 所以请帮助我进行十进制转换,我试图在开始时将所有双倍替换为十进制并且它没有变好:(。
using System;
class Program
{
static void Main()
{
Console.WriteLine(" Get PI from methods shown here");
double d = PI();
Console.WriteLine("{0:N20}",
d);
Console.WriteLine(" Get PI from the .NET Math class constant");
double d2 = Math.PI;
Console.WriteLine("{0:N20}",
d2);
}
static double PI()
{
// Returns PI
return 2 * F(1);
}
static double F(int i)
{
// Receives the call number
//To avoid so error
if (i > 60)
{
// Stop after 60 calls
return i;
}
else
{
// Return the running total with the new fraction added
return 1 + (i / (1 + (2.0 * i))) * F(i + 1);
}
}
}
Output 产量
Get PI from methods shown here 3.14159265358979000000 Get PI from the .NET Math class constant 3.14159265358979000000
从此处显示的方法获取PI 3.14159265358979000000从.NET Math类常量获取PI 3.14159265358979000000
Well, replacing double
with decimal
is a good start - and then all you need to do is change the constant from 2.0 to 2.0m: 好吧,用
decimal
替换double
是一个好的开始 - 然后你需要做的就是将常量从2.0改为2.0m:
static decimal F(int i)
{
// Receives the call number
// To avoid so error
if (i > 60)
{
// Stop after 60 calls
return i;
}
else
{
// Return the running total with the new fraction added
return 1 + (i / (1 + (2.0m * i))) * F(i + 1);
}
}
Of course it's still going to have limited precision, but slightly more than double
. 当然它的精确度仍然有限,但略高于
double
。 The result is 3.14159265358979325010
. 结果是
3.14159265358979325010
。
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