Fix compiling issue #214 on Windows VS.

src/algorithm/factorization/faust_butterfly.hpp

@@ -205,12 +205,19 @@ namespace Faust
 			return out;
 		}
 
+	// TODO: specializations should be in .cpp file
 	template<>
 		void bit_reversal_factor<double>(int nfactors, std::vector<Faust::MatSparse<double, Cpu>*> &out)
 		{
 			//nothing to do for double matrices
 		}
 
+	template<>
+		void bit_reversal_factor<float>(int nfactors, std::vector<Faust::MatSparse<float, Cpu>*> &out)
+		{
+			//nothing to do for float matrices
+		}
+
 	template<>
 		void bit_reversal_factor<std::complex<double>>(int nfactors, std::vector<Faust::MatSparse<std::complex<double>, Cpu>*>& out)
 		{