Move eigen to third party (#282)

* remove useless statement

* Add eigen to third_party dir

* remove reducdant lines

third_party/eigen/bench/basicbenchmark.cpp

@@ -0,0 +1,36 @@
+
+#include "basicbenchmark.h"
+#include <iostream>
+#include "BenchUtil.h"
+
+int main(int argc, char *argv[]) {
+  DISABLE_SSE_EXCEPTIONS();
+
+// this is the list of matrix type and size we want to bench:
+// ((suffix) (matrix size) (number of iterations))
+#define MODES \
+  ((3d)(3)(4000000))((4d)(4)(1000000))((Xd)(4)(1000000))((Xd)(20)(10000))
+//   #define MODES ((Xd)(20)(10000))
+
+#define _GENERATE_HEADER(R, ARG, EL)                     \
+  << BOOST_PP_STRINGIZE(BOOST_PP_SEQ_HEAD(EL)) << "-"    \
+  << BOOST_PP_STRINGIZE(BOOST_PP_SEQ_ELEM(1, EL)) << "x" \
+  << BOOST_PP_STRINGIZE(BOOST_PP_SEQ_ELEM(1, EL)) << "   /   "
+
+  std::cout BOOST_PP_SEQ_FOR_EACH(_GENERATE_HEADER, ~, MODES) << endl;
+
+  const int tries = 10;
+
+#define _RUN_BENCH(R, ARG, EL)                                              \
+  std::cout << ARG(BOOST_PP_CAT(Matrix, BOOST_PP_SEQ_HEAD(EL))(             \
+                       BOOST_PP_SEQ_ELEM(1, EL), BOOST_PP_SEQ_ELEM(1, EL)), \
+                   BOOST_PP_SEQ_ELEM(2, EL), tries)                         \
+            << "   ";
+
+  BOOST_PP_SEQ_FOR_EACH(_RUN_BENCH, benchBasic<LazyEval>, MODES);
+  std::cout << endl;
+  BOOST_PP_SEQ_FOR_EACH(_RUN_BENCH, benchBasic<EarlyEval>, MODES);
+  std::cout << endl;
+
+  return 0;
+}