From 1678cb3a6917428de2d34e09457d1b1393ec234e Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Tue, 17 Apr 2018 17:01:29 +1000
Subject: [PATCH] maths: add rsqrt convenience function

---
 maths.hpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/maths.hpp b/maths.hpp
index a9f0fb54..4562d655 100644
--- a/maths.hpp
+++ b/maths.hpp
@@ -214,6 +214,15 @@ namespace util {
 
     ///////////////////////////////////////////////////////////////////////////
     // exponentials
+
+    // reciprocal sqrt, provided so that we can search for usages and replace
+    // at a later point with a more efficient implementation.
+    inline float
+    rsqrt (float val)
+    {
+        return 1 / std::sqrt (val);
+    }
+
     template <
         typename BaseT,
         typename ExponentT,