5.13

1 files changed, 23 insertions, 0 deletions

diff --git a/zen/basic_math.h b/zen/basic_math.h
index d83a7f77..89d9d6c0 100644
--- a/zen/basic_math.h
+++ b/zen/basic_math.h
@@ -10,6 +10,7 @@
 #include <algorithm>
 #include <iterator>
 #include <limits>
+#include <cmath>
 #include <functional>
 #include <cassert>
 
@@ -40,6 +41,9 @@ std::pair<InputIterator, InputIterator> minMaxElement(InputIterator first, Input
 template <class InputIterator, class Compare>
 std::pair<InputIterator, InputIterator> minMaxElement(InputIterator first, InputIterator last, Compare comp);
 
+template <class T, class InputIterator> //precondition: range must be sorted!
+auto nearMatch(const T& val, InputIterator first, InputIterator last) -> typename std::iterator_traits<InputIterator>::value_type;
+
 template <class T>
 bool isNull(T value);
 
@@ -198,6 +202,25 @@ std::pair<InputIterator, InputIterator> minMaxElement(InputIterator first, Input
 }
 
 
+template <class T, class InputIterator> inline
+auto nearMatch(const T& val, InputIterator first, InputIterator last) -> typename std::iterator_traits<InputIterator>::value_type
+{
+    if (first == last)
+        return 0;
+
+    assert(std::is_sorted(first, last));
+    InputIterator it = std::lower_bound(first, last, val);
+    if (it == last)
+        return *--last;
+    if (it == first)
+        return *first;
+
+    const auto nextVal = *it;
+    const auto prevVal = *--it;
+    return val - prevVal < nextVal - val ? prevVal : nextVal;
+}
+
+
 template <class T> inline
 bool isNull(T value)
 {