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diff --git a/boost/compute/algorithm/copy_if.hpp b/boost/compute/algorithm/copy_if.hpp
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+++ b/boost/compute/algorithm/copy_if.hpp
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+//---------------------------------------------------------------------------//
+// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
+//
+// Distributed under the Boost Software License, Version 1.0
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+//
+// See http://boostorg.github.com/compute for more information.
+//---------------------------------------------------------------------------//
+
+#ifndef BOOST_COMPUTE_ALGORITHM_COPY_IF_HPP
+#define BOOST_COMPUTE_ALGORITHM_COPY_IF_HPP
+
+#include <boost/compute/algorithm/transform_if.hpp>
+#include <boost/compute/functional/identity.hpp>
+
+namespace boost {
+namespace compute {
+namespace detail {
+
+// like the copy_if() algorithm but writes the indices of the values for which
+// predicate returns true.
+template<class InputIterator, class OutputIterator, class Predicate>
+inline OutputIterator copy_index_if(InputIterator first,
+                                    InputIterator last,
+                                    OutputIterator result,
+                                    Predicate predicate,
+                                    command_queue &queue = system::default_queue())
+{
+    typedef typename std::iterator_traits<InputIterator>::value_type T;
+
+    return detail::transform_if_impl(
+        first, last, result, identity<T>(), predicate, true, queue
+    );
+}
+
+} // end detail namespace
+
+/// Copies each element in the range [\p first, \p last) for which
+/// \p predicate returns \c true to the range beginning at \p result.
+template<class InputIterator, class OutputIterator, class Predicate>
+inline OutputIterator copy_if(InputIterator first,
+                              InputIterator last,
+                              OutputIterator result,
+                              Predicate predicate,
+                              command_queue &queue = system::default_queue())
+{
+    typedef typename std::iterator_traits<InputIterator>::value_type T;
+
+    return ::boost::compute::transform_if(
+        first, last, result, identity<T>(), predicate, queue
+    );
+}
+
+} // end compute namespace
+} // end boost namespace
+
+#endif // BOOST_COMPUTE_ALGORITHM_COPY_IF_HPP