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diff --git a/src/cml/et/scalar_promotions.h b/src/cml/et/scalar_promotions.h
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+++ b/src/cml/et/scalar_promotions.h
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+/* -*- C++ -*- ------------------------------------------------------------
+ 
+Copyright (c) 2007 Jesse Anders and Demian Nave http://cmldev.net/
+
+The Configurable Math Library (CML) is distributed under the terms of the
+Boost Software License, v1.0 (see cml/LICENSE for details).
+
+ *-----------------------------------------------------------------------*/
+/** @file
+ *  @brief
+ */
+
+#ifndef scalar_promotions_h
+#define scalar_promotions_h
+
+#include <cml/core/cml_meta.h>
+
+namespace cml {
+namespace et {
+
+namespace detail {
+
+/** @class IntPromote
+ *  @brief Helper template to int-promote a type.
+ */
+template<class T> struct IntPromote
+{
+    /* Signed -> signed int, unsigned -> unsigned int: */
+    typedef typename select_switch<T,
+            unsigned char,                       unsigned int,
+            unsigned short,                      unsigned int,
+            signed char,                         int,
+            char,                                int,
+            short,                               int,
+            T,                                   T
+    >::result   result;
+};
+
+} // namespace detail
+
+/** @class ScalarPromote
+ *  @brief Template for compile-time type promotion via C promotion rules.
+ */
+template<class E1_in, class E2_in> struct ScalarPromote
+{
+
+    /* Integral-promote the types (if possible). */
+    typedef typename detail::IntPromote<E1_in>::result  E1;
+    typedef typename detail::IntPromote<E2_in>::result  E2;
+
+    /* If sizeof(long) == sizeof(unsigned int), promote to unsigned long.
+     * Otherwise, sizeof(long) > sizeof(int), so promote to long.
+     */
+    typedef typename select_if<sizeof(long) == sizeof(unsigned int),
+            unsigned long,
+            long
+    >::result   uint_promotion;
+
+    /* Do the selection on the promoted types: */
+    typedef typename select_switch<
+        type_pair<E1,E2>,
+
+#if defined(CML_USE_LONG_DOUBLE)
+        type_pair<long double,long double>,       long double,
+        type_pair<long double,E2>,                long double,
+        type_pair<E1,long double>,                long double,
+#endif
+
+        type_pair<double,double>,                 double,
+        type_pair<double,E2>,                     double,
+        type_pair<E1,double>,                     double,
+
+        type_pair<float,float>,                   float,
+        type_pair<float,E2>,                      float,
+        type_pair<E1,float>,                      float,
+
+        type_pair<E1,E2>,                         void
+
+    >::result   float_filter;
+
+    /* The promoted integral types really matter here: */
+    typedef typename select_switch<
+        type_pair<E1,E2>,
+
+        type_pair<unsigned long,unsigned long>,   unsigned long,
+        type_pair<unsigned long,E2>,              unsigned long,
+        type_pair<E1,unsigned long>,              unsigned long,
+
+        type_pair<long,long>,                     long,
+        type_pair<long,unsigned int>,             uint_promotion,
+        type_pair<unsigned int,long>,             uint_promotion,
+
+        type_pair<long,E2>,                       long,
+        type_pair<E1,long>,                       long,
+
+        type_pair<unsigned int,unsigned int>,     unsigned int,
+        type_pair<unsigned int,E2>,               unsigned int,
+        type_pair<E1,unsigned int>,               unsigned int,
+
+        type_pair<int,int>,                       int,
+        type_pair<int,E2>,                        int,
+        type_pair<E1,int>,                        int,
+
+        type_pair<E1,E2>,                         void
+
+    >::result   int_filter;
+
+    /* Deduce the final type: */
+    typedef typename select_if<
+        same_type<float_filter,void>::is_true,
+        int_filter, float_filter>::result         type;
+};
+
+} // namespace et
+} // namespace cml
+
+#endif
+
+// -------------------------------------------------------------------------
+// vim:ft=cpp