Squashed 'third_party/eigen/' content from commit 61d72f6
Change-Id: Iccc90fa0b55ab44037f018046d2fcffd90d9d025
git-subtree-dir: third_party/eigen
git-subtree-split: 61d72f6383cfa842868c53e30e087b0258177257
diff --git a/bench/vdw_new.cpp b/bench/vdw_new.cpp
new file mode 100644
index 0000000..d260404
--- /dev/null
+++ b/bench/vdw_new.cpp
@@ -0,0 +1,56 @@
+#include <iostream>
+#include <Eigen/Core>
+
+using namespace Eigen;
+
+#ifndef SCALAR
+#define SCALAR float
+#endif
+
+#ifndef SIZE
+#define SIZE 10000
+#endif
+
+#ifndef REPEAT
+#define REPEAT 10000
+#endif
+
+typedef Matrix<SCALAR, Eigen::Dynamic, 1> Vec;
+
+using namespace std;
+
+SCALAR E_VDW(const Vec &interactions1, const Vec &interactions2)
+{
+ return (interactions2.cwise()/interactions1)
+ .cwise().cube()
+ .cwise().square()
+ .cwise().square()
+ .sum();
+}
+
+int main()
+{
+ //
+ // 1 2 3 4 ... (interactions)
+ // ka . . . . ...
+ // rab . . . . ...
+ // energy . . . . ...
+ // ... ... ... ... ... ...
+ // (variables
+ // for
+ // interaction)
+ //
+ Vec interactions1(SIZE), interactions2(SIZE); // SIZE is the number of vdw interactions in our system
+ // SetupCalculations()
+ SCALAR rab = 1.0;
+ interactions1.setConstant(2.4);
+ interactions2.setConstant(rab);
+
+ // Energy()
+ SCALAR energy = 0.0;
+ for (unsigned int i = 0; i<REPEAT; ++i) {
+ energy += E_VDW(interactions1, interactions2);
+ energy *= 1 + 1e-20 * i; // prevent compiler from optimizing the loop
+ }
+ cout << "energy = " << energy << endl;
+}