diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index 11c0afde..27b97b8b 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -156,11 +156,12 @@ Changes as of now:
 ### Functions
 
 - Trig functions: common short names instead of very long names. Add sinc function.
-- Excel Functions: TDIST, TINV, BETADIST, BETAINV, GAMMADIST, GAMMAINV, NORMDIST, NORMINV, NORMSDIST, NORMSINV QUARTILE, PERCENTILE, PERCENTRANK.
-- Special Functions: BetaRegularized more robust for large arguments.
-- Special Functions: new `GammaLowerRegularizedInv`.
+- Excel functions: TDIST, TINV, BETADIST, BETAINV, GAMMADIST, GAMMAINV, NORMDIST, NORMINV, NORMSDIST, NORMSINV QUARTILE, PERCENTILE, PERCENTRANK.
+- Special functions: BetaRegularized more robust for large arguments.
+- Special functions: new `GammaLowerRegularizedInv`.
 - New distance functions in `Distance`: euclidean, manhattan, chebychev distance of arrays or generic vectors. SAD, MAE, SSD, MSE metrics. Pearson's, Canberra and Minkowski distance. Hamming distance.
 - Windows: ported windowing functions from Neodym (Hamming, Hann, Cosine, Lanczos, Gauss, Blackmann, Bartlett, ...)
+- BigInteger factorial
 
 ### Build & Packages
 
@@ -180,14 +181,15 @@ Changes as of now:
 - Integration: simplification of the double-exponential transformation api design.
 - FFT: converted to static class design and shorter names for simpler usage. Drop now redundant `Transform` class.
 - Generate: ported synthetic data generation and sampling routines from Neodym (includes all from old Signals namespace). F# module for higher order functions.
-- Euclid: modulus vs remainder, integer theory (includes all from old NumberTheory namespace).
+- Euclid: modulus vs remainder (also BigInteger), integer theory (includes all from old NumberTheory namespace).
 - Complex: common short names for Exp, Ln, Log10, Log.
 - Complex: fix issue where a *negative zero* may flip the sign in special cases (like `Atanh(2)`, where incidentally MATLAB and Mathematica do not agree on the sign either).
 - Complex: routines to return all two square and three cubic roots of a complex number.
 - Complex: More robust complex Asin/Acos for large real numbers.
 - Evaluate: routine to evaluate complex polynomials, or real polynomials at a complex point.
 - CommonParallel now also supported in .Net 3.5 and portable profiles; TaskScheduler can be replaced with custom implementation *~Thomas Ibel*
-- F# code originally imported from F# PowerPack cleaned up *~Jack Pappas*
+- F# BigRational type cleaned up and optimized *~Jack Pappas*
+- F# BigRational IsZero, IsOne, IsInteger, Reciprocal, Power operator support (**), create from fraction.
 - F# functions now use the clearer `Func` suffix instead of just `F` if they return a function.
 - Precision: reworked, now much more consistent. **If you use `AlmostEqual` with numbers-between/ULP semantics, please do review your code to make sure you're still using the expected variant!**. If you use the decimal-places semantics, you may need to decrement the digits argument to get the same behavior as before.
 - Much less null checks, our code generally only throws `ArgumentNullException` if an unexpected null argument would *not* have caused an immediate `NullReferenceException`.
diff --git a/src/Numerics/Euclid.cs b/src/Numerics/Euclid.cs
index 05bc2fce..9323c94e 100644
--- a/src/Numerics/Euclid.cs
+++ b/src/Numerics/Euclid.cs
@@ -4,7 +4,7 @@
 // http://github.com/mathnet/mathnet-numerics
 // http://mathnetnumerics.codeplex.com
 //
-// Copyright (c) 2009-2013 Math.NET
+// Copyright (c) 2009-2014 Math.NET
 //
 // Permission is hereby granted, free of charge, to any person
 // obtaining a copy of this software and associated documentation
@@ -74,6 +74,16 @@ namespace MathNet.Numerics
             return ((dividend%divisor) + divisor)%divisor;
         }
 
+#if !NOSYSNUMERICS
+        /// <summary>
+        /// Canonical Modulus. The result has the sign of the divisor.
+        /// </summary>
+        public static BigInteger Modulus(BigInteger dividend, BigInteger divisor)
+        {
+            return ((dividend%divisor) + divisor)%divisor;
+        }
+#endif
+
         /// <summary>
         /// Remainder (% operator). The result has the sign of the dividend.
         /// </summary>
@@ -106,6 +116,16 @@ namespace MathNet.Numerics
             return dividend%divisor;
         }
 
+#if !NOSYSNUMERICS
+        /// <summary>
+        /// Remainder (% operator). The result has the sign of the dividend.
+        /// </summary>
+        public static BigInteger Remainder(BigInteger dividend, BigInteger divisor)
+        {
+            return dividend%divisor;
+        }
+#endif
+
         /// <summary>
         /// Find out whether the provided 32 bit integer is an even number.
         /// </summary>
diff --git a/src/Numerics/SpecialFunctions/Factorial.cs b/src/Numerics/SpecialFunctions/Factorial.cs
index be858c46..ece7ea0d 100644
--- a/src/Numerics/SpecialFunctions/Factorial.cs
+++ b/src/Numerics/SpecialFunctions/Factorial.cs
@@ -28,13 +28,17 @@
 // OTHER DEALINGS IN THE SOFTWARE.
 // </copyright>
 
+using System;
+using MathNet.Numerics.Properties;
+
+#if !NOSYSNUMERICS
+using System.Numerics;
+#endif
+
 // ReSharper disable CheckNamespace
 namespace MathNet.Numerics
 // ReSharper restore CheckNamespace
 {
-    using System;
-    using Properties;
-
     public partial class SpecialFunctions
     {
         private const int FactorialMaxArgument = 170;
@@ -64,7 +68,7 @@ namespace MathNet.Numerics
         /// </summary>
         /// <returns>A value value! for value > 0</returns>
         /// <remarks>
-        /// If you need to multiply or divide various such factorials, consider using the logarithmic version 
+        /// If you need to multiply or divide various such factorials, consider using the logarithmic version
         /// <see cref="FactorialLn"/> instead so you can add instead of multiply and subtract instead of divide, and
         /// then exponentiate the result using <see cref="System.Math.Exp"/>. This will also circumvent the problem that
         /// factorials become very large even for small parameters.
@@ -85,6 +89,27 @@ namespace MathNet.Numerics
             return Double.PositiveInfinity;
         }
 
+#if !NOSYSNUMERICS
+        /// <summary>
+        /// Computes the factorial of an integer.
+        /// </summary>
+        public static BigInteger Factorial(BigInteger x)
+        {
+            if (x < 0)
+            {
+                throw new ArgumentOutOfRangeException("x", Resources.ArgumentPositive);
+            }
+            if (x == 0)
+            {
+                return BigInteger.One;
+            }
+
+            BigInteger r = x;
+            while (--x > 1) r *= x;
+            return r;
+        }
+#endif
+
         /// <summary>
         /// Computes the logarithmic factorial function x -> ln(x!) of an integer number > 0.
         /// </summary>
@@ -147,7 +172,7 @@ namespace MathNet.Numerics
         /// <param name="n">A nonnegative value n.</param>
         /// <param name="ni">An array of nonnegative values that sum to <paramref name="n"/>.</param>
         /// <returns>The multinomial coefficient.</returns>
-        /// <exception cref="ArgumentNullException">if <paramref name="ni"/> is <see langword="null" />.</exception>   
+        /// <exception cref="ArgumentNullException">if <paramref name="ni"/> is <see langword="null" />.</exception>
         /// <exception cref="ArgumentException">If <paramref name="n"/> or any of the <paramref name="ni"/> are negative.</exception>
         /// <exception cref="ArgumentException">If the sum of all <paramref name="ni"/> is not equal to <paramref name="n"/>.</exception>
         public static double Multinomial(int n, int[] ni)