Prefix large theta matrices with Theta as well

python/dune/perftool/sumfact/tabulation.py

@@ -146,7 +146,7 @@ class BasisTabulationMatrixArray(BasisTabulationMatrixBase):
         self.width = width
 
     def __str__(self):
-        return "_".join((t._shortname for t in self.tabs))
+        return "Theta{}".format("_".join((t._shortname for t in self.tabs)))
 
     @property
     def quadrature_size(self):