From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Tue, 2 Apr 2024 03:23:08 +0000 (-0600)
Subject: Provide a default implementation for VectorizedArray::dot_product().
X-Git-Tag: v9.6.0-rc1~416^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a86d6237351f4890f72144bedc03a808e4008938;p=dealii.git

Provide a default implementation for VectorizedArray::dot_product().
---

diff --git a/include/deal.II/base/vectorization.h b/include/deal.II/base/vectorization.h
index 58ad2e09e7..9511a853a1 100644
--- a/include/deal.II/base/vectorization.h
+++ b/include/deal.II/base/vectorization.h
@@ -334,6 +334,25 @@ public:
     return VectorizedArrayIterator<const VectorizedArrayType>(
       static_cast<const VectorizedArrayType &>(*this), width);
   }
+
+  /**
+   * A default implementation for computing the dot product between two
+   * vectorized arrays. It first forms the lane-by-lane product between
+   * the current object and the argument, and then the across-lanes
+   * sum of the product. The function returns the kind of object that
+   * the VectorizedArray::sum() function returns.
+   *
+   * This function is inherited by all derived classes and provides
+   * the dot product to them unless they override it with their own
+   * implementation (presumably using a more efficient approach).
+   */
+  auto
+  dot_product(const VectorizedArrayType &v) const
+  {
+    VectorizedArrayType p = static_cast<const VectorizedArrayType &>(*this);
+    p *= v;
+    return p.sum();
+  }
 };