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POArbitrary Precision for decimals in C# help?
 

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  1. POArbitrary Precision for decimals in C# help?
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    <p>Here is my current code for computing Pi using the chudnovsky method in c#:</p> <pre><code>using System; using System.Diagnostics; using System.IO; using java.math; namespace pi.chudnovsky { public class Program { static Double Factorial(Double fact) { //begin factorial function if (fact &lt;= 1) return 1; else return fact * Factorial(fact - 1); //loops multiplication until the factorial is reached } static Double doSummation(Double maxPower) { //begin chudnovsky summation function Double sum = 0; for (int i = 0; i &lt;= maxPower; i++) //starts at i=0 { sum += ((Math.Pow(-1, i)) * Factorial(6 * i) * (13591409 + 5451401 * i)) / (Factorial(3 * i) * Factorial(i) * Factorial(i) * Factorial(i) * Math.Pow(640320, (3 * i + 1.5))); //chudnovsky algorithm } return sum; } static void Main(string[] args) { int num; Console.WriteLine("Enter how many terms to compute Chudnovsky summation: "); //begin stopwatch Stopwatch stopwatch = new Stopwatch(); stopwatch.Start(); //parse user input num = Convert.ToInt32(Console.ReadLine()); //perform calculation Double inv = 1 / (12 * doSummation(num)); //stop stopwatch stopwatch.Stop(); //display info Console.WriteLine(inv); Console.WriteLine("3.14159265358979323846264338327950288419716939937510"); Console.WriteLine("Time elapsed: {0}", stopwatch.Elapsed.TotalMilliseconds); //write to pi.txt TextWriter pi = new StreamWriter("pi.txt"); pi.WriteLine(inv); pi.Close(); //write to stats.txt TextWriter stats = new StreamWriter("stats.txt"); stats.WriteLine(stopwatch.Elapsed.TotalMilliseconds); stats.Close(); } } } </code></pre> <p>So, I've included the J# library, and included java.math. Now when I replace all the "double"s with "BigDecimal"s, I get these compile errors:</p> <p><a href="http://f.cl.ly/items/1r2X26470d0d0n260p0p/Image%202011-11-14%20at%206.16.19%20PM.png" rel="nofollow">http://f.cl.ly/items/1r2X26470d0d0n260p0p/Image%202011-11-14%20at%206.16.19%20PM.png</a></p> <p>I know that this isn't the problem with me using Int for the loops, as it worked perfectly with Doubles. My question is, how do you resolve these errors relating to int and BigDecimal, or can you recommend another arbitrary precision library?</p> <p>I've tried using XMPIR, have gotten everything to compile, but I get:</p> <p><a href="http://f.cl.ly/items/1l3C371j2u3z3n2g3a0j/Image%202011-11-14%20at%206.20.24%20PM.png" rel="nofollow">http://f.cl.ly/items/1l3C371j2u3z3n2g3a0j/Image%202011-11-14%20at%206.20.24%20PM.png</a></p> <p>So I can I use p/invoke to include xmpir so I can use whatever the bigdecimal class is?</p> <p>Thank you for your time!</p>
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    1. COwhy would you use a recursive factorial? wouldn't a lookup be better?
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    2. COThat class does not have the operators overloaded. You have you call `subtract`, `add`, `divide` methods, respectively.
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    3. CObtw in future I would recommend copying the actual compiler output into your question, rather than linking to an image. You can select+copy it from the `View | Output` window, changing the `Show ouput from` dropdown to `Build` if necessary.
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