1 files changed, 57 insertions, 0 deletions
diff --git a/libs/numeric/odeint/performance/c_lorenz.c b/libs/numeric/odeint/performance/c_lorenz.c
new file mode 100644
index 000000000..85aba7fde
--- /dev/null
+++ b/libs/numeric/odeint/performance/c_lorenz.c
@@ -0,0 +1,57 @@
+#include <stdio.h>
+#include <time.h>
+#include <math.h>
+
+void lorenz(const double *x, double *restrict y) {
+    y[0] = 10.0 * (x[1] - x[0]);
+    y[1] = 28.0 * x[0] - x[1] - x[0] * x[2];
+    y[2] = x[0] * x[1] - (8.0 / 3.0) * x[2];
+}
+
+int main(int argc, const char *argv[])
+{
+    const int nb_steps = 20000000;
+    const double h = 1.0e-10;
+    const double h2 = 0.5 * h;
+    const double nb_loops = 21;
+    double x[3];
+    double y[3];
+    double f1[3];
+    double f2[3];
+    double f3[3];
+    double f4[3];
+    double min_time = 1E6;
+    clock_t begin, end;
+    double time_spent;
+    
+    for (int j = 0; j < nb_loops; j++) {
+        x[0] = 8.5;
+        x[1] = 3.1;
+        x[2] = 1.2;
+        begin = clock();
+        for (int k = 0; k < nb_steps; k++) {
+            lorenz(x, f1);
+            for (int i = 0; i < 3; i++) {
+                y[i] = x[i] + h2 * f1[i];
+            }
+            lorenz(y, f2);
+            for (int i = 0; i < 3; i++) {
+                y[i] = x[i] + h2 * f2[i];
+            }
+            lorenz(y, f3);
+            for (int i = 0; i < 3; i++) {
+                y[i] = x[i] + h * f3[i];
+            }
+            lorenz(y, f4);
+            for (int i = 0; i < 3; i++) {
+                x[i] = x[i] + h * (f1[i] + 2 * (f2[i] + f3[i]) + f4[i]) / 6.0;
+            }
+        }
+        end = clock();
+        min_time = fmin(min_time, (double)(end-begin)/CLOCKS_PER_SEC);
+        printf("Result: %f\t runtime: %f\n", x[0], (double)(end-begin)/CLOCKS_PER_SEC);
+    }
+    printf("Minimal Runtime: %f\n", min_time);
+    
+    return 0;
+}