From 3e9f5efbe0cc80e4d4ed333154034e3937ea1a52 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Wed, 4 Feb 2015 15:44:31 +1100
Subject: [PATCH] maths: add sinc functions

---
 maths.hpp | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/maths.hpp b/maths.hpp
index 40389da6..62311612 100644
--- a/maths.hpp
+++ b/maths.hpp
@@ -193,16 +193,21 @@ to_radians [[gnu::pure]] (T degrees)
 }
 
 
-//-----------------------------------------------------------------------------
-constexpr float
-to_radians [[gnu::pure]] (float degrees) {
-    return degrees / 180 * static_cast<float> (PI_f);
+//! Normalised sinc function
+template <typename T>
+constexpr T
+sincn [[gnu::pure]] (T x)
+{
+    return std::sin (constants<T>::PI * x) / (constants<T>::PI * x);
 }
 
 
-constexpr double
-to_radians [[gnu::pure]] (double degrees) {
-    return degrees / 180 * PI_d;
+//! Unnormalised sinc function
+template <typename T>
+constexpr T
+sincu [[gnu::pure]] (T x)
+{
+    return std::sin (x) / x;
 }