Refactored a bunch of the matrix code into a cleaner form. I also added a

cost member to all the matrix expressions so that the complexity of an
expression can be measured and temporaries introduced when appropriate.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402732

dlib/is_kind.h

@@ -45,7 +45,7 @@ namespace dlib
 
 // ----------------------------------------------------------------------------------------
 
-    template <typename T>
+    template <typename T, typename helper = void>
     struct is_matrix : public default_is_kind_value  
     {
         /*!
@@ -54,6 +54,9 @@ namespace dlib
             - else
                 - is_matrix<T>::value == false
         !*/
+
+        // Don't set the helper to anything.  Just let it be void.
+        ASSERT_ARE_SAME_TYPE(helper,void);
     };
 
 // ----------------------------------------------------------------------------------------

dlib/matrix/matrix_abstract.h

@@ -167,6 +167,7 @@ namespace dlib
         const static long NR = EXP::NR;
         const static long NC = EXP::NC;
         typedef matrix<type,NR,NC, mem_manager_type> matrix_type;
+        const static long cost = EXP::cost;
 
         matrix_exp (
             const EXP& exp

dlib/matrix/matrix_assign.h

@@ -50,6 +50,9 @@ namespace dlib
 
 // ----------------------------------------------------------------------------------------
 
+// TODO
+#if 0
+
     template <
         typename matrix_dest_type,
         typename EXP1,
@@ -117,6 +120,7 @@ namespace dlib
 
 // ----------------------------------------------------------------------------------------
 
+#endif
 
 }
 

dlib/test/matrix2.cpp

@@ -300,7 +300,13 @@ namespace
         DLIB_CASSERT((round(m2*m1) == identity_matrix<double,4>()),"");
         DLIB_CASSERT((round(tmp(m2*m1)) == identity_matrix<double,4>()),"");
 
-        DLIB_CASSERT(round(m2*10000) == round(inv(m1)*10000),"");
+        DLIB_CASSERT(round(m2*10000) == round(inv(m1)*10000),
+                     round(m2*10000) - round(inv(m1)*10000)
+                     << "\n\n" << round(m2*10000)
+                     << "\n\n" << round(inv(m1)*10000)
+                     << "\n\n" << m2 
+                     << "\n\n" << inv(m1) 
+                     );
         DLIB_CASSERT(m1 == abs(-1*m1),"");
         DLIB_CASSERT(abs(m2) == abs(-1*m2),"");