Fix LaTeX display of continuous maps with SymPy expressions

src/sage/manifolds/chart_func.py

@@ -603,7 +603,6 @@ def display(self):
 
         """
         from sage.tensor.modules.format_utilities import FormattedExpansion
-        from sage.misc.latex import latex
         curr = self._calc_method._current
         expr = self.expr(curr)
         if (curr == 'SR' and
@@ -684,7 +683,6 @@ def __call__(self, *coords, **options):
             xx = [x._sympy_() for x in self._chart._xx]
             co = [calc._tranf['sympy'](c) for c in coords]
         substitutions = dict(zip(xx, co))
-#         print("self._express: {}".format(self._express))
         resu = self.expr(curr).subs(substitutions)
         if 'simplify' in options:
             if options['simplify']:

src/sage/manifolds/continuous_map.py

@@ -976,6 +976,22 @@ def display(self, chart1=None, chart2=None):
             on U: (x, y) |--> (X, Y, Z) = (2*x/(x^2 + y^2 + 1), 2*y/(x^2 + y^2 + 1), (x^2 + y^2 - 1)/(x^2 + y^2 + 1))
             on V: (u, v) |--> (X, Y, Z) = (2*u/(u^2 + v^2 + 1), 2*v/(u^2 + v^2 + 1), -(u^2 + v^2 - 1)/(u^2 + v^2 + 1))
 
+        Display when SymPy is the symbolic engine::
+
+            sage: M.set_calculus_method('sympy')
+            sage: N.set_calculus_method('sympy')
+            sage: Phi.display(c_xy, c_cart)
+            Phi: S^2 --> R^3
+            on U: (x, y) |--> (X, Y, Z) = (2*x/(x**2 + y**2 + 1),
+             2*y/(x**2 + y**2 + 1), (x**2 + y**2 - 1)/(x**2 + y**2 + 1))
+            sage: latex(Phi.display(c_xy, c_cart))
+            \begin{array}{llcl} \Phi:& S^2 & \longrightarrow & \RR^3
+             \\ \mbox{on}\ U : & \left(x, y\right) & \longmapsto
+             & \left(X, Y, Z\right) = \left(\frac{2 x}{x^{2} + y^{2} + 1},
+               \frac{2 y}{x^{2} + y^{2} + 1},
+               \frac{x^{2} + y^{2} - 1}{x^{2} + y^{2} + 1}\right)
+             \end{array}
+
         """
         from sage.misc.latex import latex
         from sage.tensor.modules.format_utilities import FormattedExpansion
@@ -986,7 +1002,8 @@ def _display_expression(self, chart1, chart2, result):
             """
             from sage.misc.latex import latex
             try:
-                expression = self.expr(chart1, chart2)
+                coord_func = self.coord_functions(chart1, chart2)
+                expression = coord_func.expr()
                 coords1 = chart1[:]
                 if len(coords1) == 1:
                     coords1 = coords1[0]
@@ -1005,21 +1022,21 @@ def _display_expression(self, chart1, chart2, result):
                 if chart2 == chart1:
                     if len(expression) == 1:
                         result._txt += repr(expression[0]) + "\n"
-                        result._latex += latex(expression[0]) + r"\\"
+                        result._latex += latex(coord_func[0]) + r"\\"
                     else:
                         result._txt += repr(expression) + "\n"
-                        result._latex += latex(expression) + r"\\"
+                        result._latex += latex(coord_func) + r"\\"
                 else:
                     if len(expression) == 1:
                         result._txt += repr(coords2[0]) + " = " + \
                                       repr(expression[0]) + "\n"
                         result._latex += latex(coords2[0]) + " = " + \
-                                        latex(expression[0]) + r"\\"
+                                        latex(coord_func[0]) + r"\\"
                     else:
                         result._txt += repr(coords2) + " = " + \
                                       repr(expression) + "\n"
                         result._latex += latex(coords2) + " = " + \
-                                        latex(expression) + r"\\"
+                                        latex(coord_func) + r"\\"
             except (TypeError, ValueError):
                 pass