From b885294b77a5bc22d5681b0cd0f219acd08a662e Mon Sep 17 00:00:00 2001
From: Vivien Kraus <vivien@planete-kraus.eu>
Date: Fri, 19 Mar 2021 16:59:39 +0100
Subject: Initial commit

---
 src/strats.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 src/strats.c

(limited to 'src/strats.c')

diff --git a/src/strats.c b/src/strats.c
new file mode 100644
index 0000000..1c5ce53
--- /dev/null
+++ b/src/strats.c
@@ -0,0 +1,52 @@
+#include <stdlib.h>
+
+static inline void
+product (size_t n,
+	 size_t omega,
+	 const double *restrict temporal_dependency,
+	 const double *restrict vector,
+	 double *restrict out)
+{
+  size_t i;
+  #pragma omp parallel for
+  for (i = 0; i < n; i++)
+    {
+      size_t j;
+      out[i] = 0;
+      /* Backward: */
+      for (j = 0; j < omega; j++)
+	{
+	  if (i > j)
+	    {
+	      const double x = vector[i - j - 1];
+	      const double coefficient = temporal_dependency[j];
+	      out[i] += coefficient * (vector[i] - x);
+	    }
+	}
+      /* Forward: */
+      for (j = 0; j < omega; j++)
+	{
+	  if (i + j + 1 < n)
+	    {
+	      const double x = vector[i + j + 1];
+	      const double coefficient = temporal_dependency[j];
+	      out[i] += coefficient * (vector[i] - x);
+	    }
+	}
+    }
+}
+
+void
+strats_compute_laplacian_matrix_product (int *n,
+					 int *d,
+					 int *omega,
+					 double *temporal_dependency,
+					 double *x,
+					 double *out)
+{
+  int j;
+  for (j = 0; j < *d; j++)
+    {
+      product (*n, *omega, temporal_dependency, x + j * (*n), out + j * (*n));
+    }
+}
-- 
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