Fixed a compile time bug in the pinv() function. It didn't compile

when used on statically sized matrices when they weren't square.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402620

dlib/matrix/matrix_utilities.h

@@ -2429,7 +2429,7 @@ namespace dlib
     template <
         typename EXP
         >
-    inline const typename matrix_exp<EXP>::matrix_type pinv (
+    inline const matrix<typename EXP::type,EXP::NC,EXP::NR,typename EXP::mem_manager_type> pinv ( 
         const matrix_exp<EXP>& m
     )
     { 

dlib/matrix/matrix_utilities_abstract.h

@@ -707,13 +707,13 @@ namespace dlib
 
 // ----------------------------------------------------------------------------------------
 
-    const matrix_exp::matrix_type pinv (
+    const matrix pinv (
         const matrix_exp& m
     );
     /*!
         ensures
             - returns the Moore-Penrose pseudoinverse of m.
-            - The returned matrix has m.nr() columns and m.nc() rows.
+            - The returned matrix has m.nc() rows and m.nr() columns.
     !*/
 
 // ----------------------------------------------------------------------------------------

dlib/test/matrix.cpp

@@ -910,6 +910,26 @@ namespace
         }
 
 
+        {
+            matrix<double,5,2> m;
+
+            for (long r = 0; r < m.nr(); ++r)
+            {
+                for (long c = 0; c < m.nc(); ++c)
+                {
+                    m(r,c) = r*c; 
+                }
+            }
+
+            m = cos(exp(m));
+
+
+            matrix<double> mi = pinv(m ); 
+            DLIB_CASSERT(mi.nr() == m.nc(),"");
+            DLIB_CASSERT(mi.nc() == m.nr(),"");
+            DLIB_CASSERT((equal(round_zeros(mi*m,0.000001) , identity_matrix<double,2>())),"");
+        }
+
         {
             matrix<double> m(5,2);