Update demo_tnt-elements.py

super vs subdegree

python/demo/demo_tnt-elements.py

@@ -60,8 +60,9 @@
 #
 # We begin by defining a basis of the polynomial space spanned by the
 # TNT element, which is defined in terms of the orthogonal Legendre
-# polynomials on the cell. For a degree 2 element (here, we shift the 
-# degree by 1 to allign with the definition of other elements), the polynomial set
+# polynomials on the cell. For a degree 2 element (here, we use the 
+# superdegree rather than the conventional subdegree to allign with
+# the definition of other elements), the polynomial set
 # contains $1$, $y$, $y^2$, $x$, $xy$, $xy^2$, $x^2$, and $x^2y$, which
 # are the first 8 polynomials in the degree 2 set of polynomials on a
 # quadrilateral. We create an $8 \times 9$  matrix (number of dofs by