RootFinding: OfFunctionAndDerivative fall back to Bisection instead of Brent (more robust)

src/Numerics/FindRoots.cs

@@ -38,6 +38,7 @@ namespace MathNet.Numerics
         public static double OfFunction(Func<double, double> f, double lowerBound, double upperBound, double accuracy = 1e-8)
         {
             double root;
+
             if (Brent.TryFindRoot(f, lowerBound, upperBound, accuracy, 100, out root))
             {
                 return root;
@@ -54,11 +55,13 @@ namespace MathNet.Numerics
         public static double OfFunctionAndDerivative(Func<double, double> f, Func<double, double> df, double lowerBound, double upperBound, double accuracy = 1e-8)
         {
             double root;
+
             if (RobustNewtonRaphson.TryFindRoot(f, df, lowerBound, upperBound, accuracy, 100, 20, out root))
             {
                 return root;
             }
-            if (Brent.TryFindRoot(f, lowerBound, upperBound, accuracy, 100, out root))
+
+            if (Bisection.TryFindRoot(f, lowerBound, upperBound, accuracy, 100, out root))
             {
                 return root;
             }