diff --git a/bench/benchmarkX.cpp b/bench/benchmarkX.cpp
new file mode 100644
index 0000000..8e4b60c
--- /dev/null
+++ b/bench/benchmarkX.cpp
@@ -0,0 +1,36 @@
+// g++ -fopenmp -I .. -O3 -DNDEBUG -finline-limit=1000 benchmarkX.cpp -o b && time ./b
+
+#include <iostream>
+
+#include <Eigen/Core>
+
+using namespace std;
+using namespace Eigen;
+
+#ifndef MATTYPE
+#define MATTYPE MatrixXLd
+#endif
+
+#ifndef MATSIZE
+#define MATSIZE 400
+#endif
+
+#ifndef REPEAT
+#define REPEAT 100
+#endif
+
+int main(int argc, char *argv[])
+{
+	MATTYPE I = MATTYPE::Ones(MATSIZE,MATSIZE);
+	MATTYPE m(MATSIZE,MATSIZE);
+	for(int i = 0; i < MATSIZE; i++) for(int j = 0; j < MATSIZE; j++)
+	{
+		m(i,j) = (i+j+1)/(MATSIZE*MATSIZE);
+	}
+	for(int a = 0; a < REPEAT; a++)
+	{
+		m = I + 0.0001 * (m + m*m);
+	}
+	cout << m(0,0) << endl;
+	return 0;
+}