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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 <complex>
+#include <cml/core/cml_meta.h>
+
+namespace cml {
+namespace et {
+
+/* The type promotion code below is a slightly modified version of:
+ * http://ubiety.uwaterloo.ca/~tveldhui/papers/techniques/techniques01.html
+ */
+namespace detail {
+
+template<class T>
+struct precision_trait {
+    enum { precisionRank = 0,
+           knowPrecisionRank = 0 };
+};
+
+#define DECLARE_PRECISION(T,rank)             \
+    template<>                                \
+    struct precision_trait< T > {             \
+        enum { precisionRank = rank,          \
+           knowPrecisionRank = 1 };           \
+    };
+
+DECLARE_PRECISION(int,100)
+DECLARE_PRECISION(unsigned int,200)
+DECLARE_PRECISION(long,300)
+DECLARE_PRECISION(unsigned long,400)
+
+DECLARE_PRECISION(long long,425)
+DECLARE_PRECISION(unsigned long long,475)
+
+DECLARE_PRECISION(float,500)
+DECLARE_PRECISION(double,600)
+DECLARE_PRECISION(long double,700)
+DECLARE_PRECISION(std::complex<float>,800)
+DECLARE_PRECISION(std::complex<double>,900)
+DECLARE_PRECISION(std::complex<long double>,1000)
+
+template<class T>
+struct autopromote_trait {
+    typedef T T_numtype;
+};
+
+#define DECLARE_AUTOPROMOTE(T1,T2)        \
+    template<>                            \
+    struct autopromote_trait<T1> {        \
+      typedef T2 T_numtype;               \
+    };
+
+// These are the odd cases where small integer types
+// are automatically promoted to int or unsigned int for
+// arithmetic.
+DECLARE_AUTOPROMOTE(bool, int)
+DECLARE_AUTOPROMOTE(char, int)
+DECLARE_AUTOPROMOTE(unsigned char, int)
+DECLARE_AUTOPROMOTE(short int, int)
+DECLARE_AUTOPROMOTE(short unsigned int, unsigned int)
+
+template<class T1, class T2, int promoteToT1>
+struct promote2 {
+    typedef T1 T_promote;
+};
+
+template<class T1, class T2>
+struct promote2<T1,T2,0> {
+    typedef T2 T_promote;
+};
+
+template<class T1_orig, class T2_orig>
+struct promote_trait {
+
+    // Need to remove const-ness:
+    typedef typename cml::remove_const<T1_orig>::type T1_non_const;
+    typedef typename cml::remove_const<T2_orig>::type T2_non_const;
+
+    // Handle promotion of small integers to int/unsigned int
+    typedef typename autopromote_trait<T1_non_const>::T_numtype T1;
+    typedef typename autopromote_trait<T2_non_const>::T_numtype T2;
+
+    // True if T1 is higher ranked
+    enum {
+      T1IsBetter =
+        (int) precision_trait<T1>::precisionRank >
+          (int) precision_trait<T2>::precisionRank,
+
+    // True if we know ranks for both T1 and T2
+      knowBothRanks =
+        precision_trait<T1>::knowPrecisionRank
+      && precision_trait<T2>::knowPrecisionRank,
+
+    // True if we know T1 but not T2
+      knowT1butNotT2 =  precision_trait<T1>::knowPrecisionRank
+        && !(precision_trait<T2>::knowPrecisionRank),
+
+    // True if we know T2 but not T1
+      knowT2butNotT1 =  precision_trait<T2>::knowPrecisionRank
+        && !(precision_trait<T1>::knowPrecisionRank),
+
+    // True if T1 is bigger than T2
+      T1IsLarger = sizeof(T1) >= sizeof(T2),
+
+    // We know T1 but not T2: true
+    // We know T2 but not T1: false
+    // Otherwise, if T1 is bigger than T2: true
+      defaultPromotion = knowT1butNotT2 ? false :
+         (knowT2butNotT1 ? true : T1IsLarger)
+    };
+
+    // If we have both ranks, then use them.
+    // If we have only one rank, then use the unknown type.
+    // If we have neither rank, then promote to the larger type.
+
+    enum {
+      promoteToT1 = (knowBothRanks ? T1IsBetter : defaultPromotion) 
+                        ? 1 : 0
+    };
+
+    typedef typename promote2<T1,T2,promoteToT1>::T_promote T_promote;
+};
+
+} // namespace detail
+
+/** Defers to detail::promote_trait<>. */
+template<class E1, class E2> struct ScalarPromote
+{
+    typedef typename detail::promote_trait<E1,E2>::T_promote type;
+};
+
+} // namespace et
+} // namespace cml
+
+#endif
+
+// -------------------------------------------------------------------------
+// vim:ft=cpp