Fixing the linear diffusion.

src/matrix/tnlMatrix.h

@@ -127,7 +127,8 @@ class tnlMatrix : public tnlObject
 
    bool load( const tnlString& fileName );
 
-   tnlMatrix< Real, Device, Index >& operator = ( const tnlMatrix< Real, Device, Index >& matrix );
+   template< typename Real2 >
+   tnlMatrix< Real, Device, Index >& operator = ( const tnlMatrix< Real2, Device, Index >& matrix );
 
    /*!
     * Computes permutation of the rows such that the rows would be

src/schemes/diffusion/tnlLinearDiffusion.h

@@ -21,6 +21,7 @@
 #include <mesh/tnlGrid.h>
 #include <mesh/tnlIdenticalGridGeometry.h>
 #include <core/tnlHost.h>
+#include <core/tnlSharedVector.h>
 
 template< typename Mesh >
 class tnlLinearDiffusion

src/schemes/euler/fvm/tnlLaxFridrichs.h

@@ -24,7 +24,7 @@
 #include <schemes/gradient/tnlCentralFDMGradient.h>
 
 template< typename MeshType,
-          typename PressureGradient >
+          typename PressureGradient = tnlCentralFDMGradient >
 class tnlLaxFridrichs
 {
 };