Merge pull request #248 from evelinag/fix-matrix_normal_density

MatrixNormal density computation switched row and column covariance

src/Numerics/Distributions/MatrixNormal.cs

@@ -205,7 +205,7 @@ namespace MathNet.Numerics.Distributions
             var cholV = _v.Cholesky();
             var cholK = _k.Cholesky();
 
-            return Math.Exp(-0.5*cholV.Solve(a.Transpose()*cholK.Solve(a)).Trace())
+            return Math.Exp(-0.5*cholK.Solve(a.Transpose()*cholV.Solve(a)).Trace())
                    /Math.Pow(2.0*Constants.Pi, x.RowCount*x.ColumnCount/2.0)
                    /Math.Pow(cholV.Determinant, x.RowCount/2.0)
                    /Math.Pow(cholK.Determinant, x.ColumnCount/2.0);