Unicode symbol 2202 (partial) for the text display of coordinate frames

src/doc/en/thematic_tutorials/vector_calculus/vector_calc_advanced.rst

@@ -58,9 +58,9 @@ while there are five vector frames defined on `\mathbb{E}^3`::
 
     sage: E.frames()
     [Coordinate frame (E^3, (e_x,e_y,e_z)),
-     Coordinate frame (E^3, (d/dr,d/dth,d/dph)),
+     Coordinate frame (E^3, (∂/∂r,∂/∂th,∂/∂ph)),
      Vector frame (E^3, (e_r,e_th,e_ph)),
-     Coordinate frame (E^3, (d/drh,d/dph,d/dz)),
+     Coordinate frame (E^3, (∂/∂rh,∂/∂ph,∂/∂z)),
      Vector frame (E^3, (e_rh,e_ph,e_z))]
 
 Indeed, there are two frames associated with each of the three coordinate
@@ -85,9 +85,9 @@ On the other side, the coordinate frames `\left(\frac{\partial}{\partial r},
 coordinate charts::
 
     sage: spherical.frame()
-    Coordinate frame (E^3, (d/dr,d/dth,d/dph))
+    Coordinate frame (E^3, (∂/∂r,∂/∂th,∂/∂ph))
     sage: cylindrical.frame()
-    Coordinate frame (E^3, (d/drh,d/dph,d/dz))
+    Coordinate frame (E^3, (∂/∂rh,∂/∂ph,∂/∂z))
 
 
 Charts as maps `\mathbb{E}^3 \rightarrow \mathbb{R}^3`
@@ -346,9 +346,9 @@ vector frames defined on `\mathbb{E}^3`::
 
     sage: XE.bases()
     [Coordinate frame (E^3, (e_x,e_y,e_z)),
-     Coordinate frame (E^3, (d/dr,d/dth,d/dph)),
+     Coordinate frame (E^3, (∂/∂r,∂/∂th,∂/∂ph)),
      Vector frame (E^3, (e_r,e_th,e_ph)),
-     Coordinate frame (E^3, (d/drh,d/dph,d/dz)),
+     Coordinate frame (E^3, (∂/∂rh,∂/∂ph,∂/∂z)),
      Vector frame (E^3, (e_rh,e_ph,e_z))]
 
 
@@ -385,9 +385,9 @@ The bases on `T_p\mathbb{E}^3` are inherited from the vector frames of
 
     sage: Tp.bases()
     [Basis (e_x,e_y,e_z) on the Tangent space at Point p on the Euclidean space E^3,
-     Basis (d/dr,d/dth,d/dph) on the Tangent space at Point p on the Euclidean space E^3,
+     Basis (∂/∂r,∂/∂th,∂/∂ph) on the Tangent space at Point p on the Euclidean space E^3,
      Basis (e_r,e_th,e_ph) on the Tangent space at Point p on the Euclidean space E^3,
-     Basis (d/drh,d/dph,d/dz) on the Tangent space at Point p on the Euclidean space E^3,
+     Basis (∂/∂rh,∂/∂ph,∂/∂z) on the Tangent space at Point p on the Euclidean space E^3,
      Basis (e_rh,e_ph,e_z) on the Tangent space at Point p on the Euclidean space E^3]
 
 For instance, we have::

src/doc/en/thematic_tutorials/vector_calculus/vector_calc_change.rst

@@ -204,7 +204,7 @@ At this stage, `\mathbb{E}^3` is endowed with three vector frames::
 
     sage: E.frames()
     [Coordinate frame (E^3, (e_x,e_y,e_z)),
-     Coordinate frame (E^3, (d/dr,d/dth,d/dph)),
+     Coordinate frame (E^3, (∂/∂r,∂/∂th,∂/∂ph)),
      Vector frame (E^3, (e_r,e_th,e_ph))]
 
 The second one is the *coordinate* frame `\left(\frac{\partial}{\partial r},
@@ -254,9 +254,9 @@ chart ``spherical``)::
 
     sage: for vec in spherical_frame:
     ....:     vec.display(spherical.frame(), spherical)
-    e_r = d/dr
-    e_th = 1/r d/dth
-    e_ph = 1/(r*sin(th)) d/dph
+    e_r = ∂/∂r
+    e_th = 1/r ∂/∂th
+    e_ph = 1/(r*sin(th)) ∂/∂ph
 
 
 Introducing cylindrical coordinates
@@ -299,9 +299,9 @@ There are now five vector frames defined on `\mathbb{E}^3`::
 
     sage: E.frames()
     [Coordinate frame (E^3, (e_x,e_y,e_z)),
-     Coordinate frame (E^3, (d/dr,d/dth,d/dph)),
+     Coordinate frame (E^3, (∂/∂r,∂/∂th,∂/∂ph)),
      Vector frame (E^3, (e_r,e_th,e_ph)),
-     Coordinate frame (E^3, (d/drh,d/dph,d/dz)),
+     Coordinate frame (E^3, (∂/∂rh,∂/∂ph,∂/∂z)),
      Vector frame (E^3, (e_rh,e_ph,e_z))]
 
 The orthonormal frame associated with cylindrical coordinates is
@@ -359,9 +359,9 @@ chart ``cylindrical``)::
 
     sage: for vec in cylindrical_frame:
     ....:     vec.display(cylindrical.frame(), cylindrical)
-    e_rh = d/drh
-    e_ph = 1/rh d/dph
-    e_z = d/dz
+    e_rh = ∂/∂rh
+    e_ph = 1/rh ∂/∂ph
+    e_z = ∂/∂z
 
 
 How to evaluate the coordinates of a point in various systems

src/doc/en/thematic_tutorials/vector_calculus/vector_calc_curvilinear.rst

@@ -52,10 +52,10 @@ The coordinate ranges are::
 `(e_r, e_\theta, e_\phi)` associated with spherical coordinates::
 
     sage: E.frames()
-    [Coordinate frame (E^3, (d/dr,d/dth,d/dph)),
+    [Coordinate frame (E^3, (∂/∂r,∂/∂th,∂/∂ph)),
      Vector frame (E^3, (e_r,e_th,e_ph))]
 
-In the above output, ``(d/dr,d/dth,d/dph)`` =
+In the above output, ``(∂/∂r,∂/∂th,∂/∂ph)`` =
 `\left(\frac{\partial}{\partial r}, \frac{\partial}{\partial\theta}, \frac{\partial}{\partial \phi}\right)`
 is the *coordinate* frame associated with `(r,\theta,\phi)`; it is
 not an orthonormal frame and will not be used below. The default frame is

src/doc/en/thematic_tutorials/vector_calculus/vector_calc_plane.rst

@@ -512,7 +512,7 @@ while there are three vector frames defined on `\mathbb{E}^2`::
 
     sage: E.frames()
     [Coordinate frame (E^2, (e_x,e_y)),
-     Coordinate frame (E^2, (d/dr,d/dph)),
+     Coordinate frame (E^2, (∂/∂r,∂/∂ph)),
      Vector frame (E^2, (e_r,e_ph))]
 
 Indeed, there are two frames associated with polar coordinates: the coordinate
@@ -621,7 +621,7 @@ vector frames defined on `\mathbb{E}^2`::
 
     sage: XE.bases()
     [Coordinate frame (E^2, (e_x,e_y)),
-     Coordinate frame (E^2, (d/dr,d/dph)),
+     Coordinate frame (E^2, (∂/∂r,∂/∂ph)),
      Vector frame (E^2, (e_r,e_ph))]
 
 

src/sage/manifolds/differentiable/affine_connection.py

@@ -135,17 +135,17 @@ class AffineConnection(SageObject):
 
         sage: nab[1,1,2], nab[3,2,3] = x^2, y*z  # Gamma^1_{12} = x^2, Gamma^3_{23} = yz
         sage: nab._coefficients
-        {Coordinate frame (M, (d/dx,d/dy,d/dz)): 3-indices components w.r.t.
-         Coordinate frame (M, (d/dx,d/dy,d/dz))}
+        {Coordinate frame (M, (∂/∂x,∂/∂y,∂/∂z)): 3-indices components w.r.t.
+         Coordinate frame (M, (∂/∂x,∂/∂y,∂/∂z))}
 
     If not the default one, the vector frame w.r.t. which the connection
     coefficients are defined can be specified as the first argument inside the
     square brackets; hence the above definition is equivalent to::
 
         sage: nab[c_xyz.frame(), 1,1,2], nab[c_xyz.frame(),3,2,3] = x^2, y*z
         sage: nab._coefficients
-        {Coordinate frame (M, (d/dx,d/dy,d/dz)): 3-indices components w.r.t.
-         Coordinate frame (M, (d/dx,d/dy,d/dz))}
+        {Coordinate frame (M, (∂/∂x,∂/∂y,∂/∂z)): 3-indices components w.r.t.
+         Coordinate frame (M, (∂/∂x,∂/∂y,∂/∂z))}
 
     Unset components are initialized to zero::
 
@@ -267,19 +267,19 @@ class AffineConnection(SageObject):
         sage: a = M.vector_field({eU: [-y,x]}, name='a')
         sage: a.add_comp_by_continuation(eV, W, c_uv)
         sage: a.display(eU)
-        a = -y d/dx + x d/dy
+        a = -y ∂/∂x + x ∂/∂y
         sage: a.display(eV)
-        a = v d/du - u d/dv
+        a = v ∂/∂u - u ∂/∂v
         sage: da = nab(a) ; da
         Tensor field nabla(a) of type (1,1) on the 2-dimensional differentiable
          manifold M
         sage: da.display(eU)
-        nabla(a) = -x*y d/dx⊗dx - d/dx⊗dy + d/dy⊗dx - x*y^2 d/dy⊗dy
+        nabla(a) = -x*y ∂/∂x⊗dx - ∂/∂x⊗dy + ∂/∂y⊗dx - x*y^2 ∂/∂y⊗dy
         sage: da.display(eV)
-        nabla(a) = (-1/16*u^3 + 1/16*u^2*v + 1/16*(u + 2)*v^2 - 1/16*v^3 - 1/8*u^2) d/du⊗du
-         + (1/16*u^3 - 1/16*u^2*v - 1/16*(u - 2)*v^2 + 1/16*v^3 - 1/8*u^2 + 1) d/du⊗dv
-         + (1/16*u^3 - 1/16*u^2*v - 1/16*(u - 2)*v^2 + 1/16*v^3 - 1/8*u^2 - 1) d/dv⊗du
-         + (-1/16*u^3 + 1/16*u^2*v + 1/16*(u + 2)*v^2 - 1/16*v^3 - 1/8*u^2) d/dv⊗dv
+        nabla(a) = (-1/16*u^3 + 1/16*u^2*v + 1/16*(u + 2)*v^2 - 1/16*v^3 - 1/8*u^2) ∂/∂u⊗du
+         + (1/16*u^3 - 1/16*u^2*v - 1/16*(u - 2)*v^2 + 1/16*v^3 - 1/8*u^2 + 1) ∂/∂u⊗dv
+         + (1/16*u^3 - 1/16*u^2*v - 1/16*(u - 2)*v^2 + 1/16*v^3 - 1/8*u^2 - 1) ∂/∂v⊗du
+         + (-1/16*u^3 + 1/16*u^2*v + 1/16*(u + 2)*v^2 - 1/16*v^3 - 1/8*u^2) ∂/∂v⊗dv
 
     A few tests::
 
@@ -317,19 +317,19 @@ class AffineConnection(SageObject):
         sage: a = M.vector_field({eU: [-y,x]}, name='a')
         sage: a.add_comp_by_continuation(eV, W, c_uv)
         sage: a.display(eU)
-        a = -y d/dx + x d/dy
+        a = -y ∂/∂x + x ∂/∂y
         sage: a.display(eV)
-        a = v d/du - u d/dv
+        a = v ∂/∂u - u ∂/∂v
         sage: da = nab(a) ; da
         Tensor field nabla(a) of type (1,1) on the 2-dimensional differentiable
          manifold M
         sage: da.display(eU)
-        nabla(a) = -x*y d/dx⊗dx - d/dx⊗dy + d/dy⊗dx - x*y**2 d/dy⊗dy
+        nabla(a) = -x*y ∂/∂x⊗dx - ∂/∂x⊗dy + ∂/∂y⊗dx - x*y**2 ∂/∂y⊗dy
         sage: da.display(eV)
-        nabla(a) = (-u**3/16 + u**2*v/16 - u**2/8 + u*v**2/16 - v**3/16 + v**2/8) d/du⊗du
-         + (u**3/16 - u**2*v/16 - u**2/8 - u*v**2/16 + v**3/16 + v**2/8 + 1) d/du⊗dv
-         + (u**3/16 - u**2*v/16 - u**2/8 - u*v**2/16 + v**3/16 + v**2/8 - 1) d/dv⊗du
-         + (-u**3/16 + u**2*v/16 - u**2/8 + u*v**2/16 - v**3/16 + v**2/8) d/dv⊗dv
+        nabla(a) = (-u**3/16 + u**2*v/16 - u**2/8 + u*v**2/16 - v**3/16 + v**2/8) ∂/∂u⊗du
+         + (u**3/16 - u**2*v/16 - u**2/8 - u*v**2/16 + v**3/16 + v**2/8 + 1) ∂/∂u⊗dv
+         + (u**3/16 - u**2*v/16 - u**2/8 - u*v**2/16 + v**3/16 + v**2/8 - 1) ∂/∂v⊗du
+         + (-u**3/16 + u**2*v/16 - u**2/8 + u*v**2/16 - v**3/16 + v**2/8) ∂/∂v⊗dv
 
     To make affine connections hashable, they have to be set immutable before::
 
@@ -612,7 +612,7 @@ def _new_coef(self, frame):
             sage: X.<x,y> = M.chart()
             sage: nab = M.affine_connection('nabla', latex_name=r'\nabla')
             sage: nab._new_coef(X.frame())
-            3-indices components w.r.t. Coordinate frame (M, (d/dx,d/dy))
+            3-indices components w.r.t. Coordinate frame (M, (∂/∂x,∂/∂y))
 
         """
         from sage.tensor.modules.comp import Components
@@ -659,11 +659,11 @@ def coef(self, frame=None):
             sage: nab = M.affine_connection('nabla', r'\nabla')
             sage: nab[1,1,2], nab[3,2,3] = x^2, y*z  # Gamma^1_{12} = x^2, Gamma^3_{23} = yz
             sage: nab.coef()
-            3-indices components w.r.t. Coordinate frame (M, (d/dx,d/dy,d/dz))
+            3-indices components w.r.t. Coordinate frame (M, (∂/∂x,∂/∂y,∂/∂z))
             sage: type(nab.coef())
             <class 'sage.tensor.modules.comp.Components'>
             sage: M.default_frame()
-            Coordinate frame (M, (d/dx,d/dy,d/dz))
+            Coordinate frame (M, (∂/∂x,∂/∂y,∂/∂z))
             sage: nab.coef() is nab.coef(c_xyz.frame())
             True
             sage: nab.coef()[:]  # full list of coefficients:
@@ -735,9 +735,9 @@ class :class:`~sage.tensor.modules.comp.Components`; if such
             sage: X.<x,y> = M.chart()
             sage: nab = M.affine_connection('nabla', latex_name=r'\nabla')
             sage: eX = X.frame(); eX
-            Coordinate frame (M, (d/dx,d/dy))
+            Coordinate frame (M, (∂/∂x,∂/∂y))
             sage: nab.set_coef(eX)
-            3-indices components w.r.t. Coordinate frame (M, (d/dx,d/dy))
+            3-indices components w.r.t. Coordinate frame (M, (∂/∂x,∂/∂y))
             sage: nab.set_coef(eX)[1,2,1] = x*y
             sage: nab.display(eX)
             Gam^x_yx = x*y
@@ -747,7 +747,7 @@ class :class:`~sage.tensor.modules.comp.Components`; if such
 
             sage: nab.set_coef()[1,2,1] = x*y
             sage: nab.set_coef()
-            3-indices components w.r.t. Coordinate frame (M, (d/dx,d/dy))
+            3-indices components w.r.t. Coordinate frame (M, (∂/∂x,∂/∂y))
             sage: nab.set_coef()[1,2,1] = x*y
             sage: nab.display()
             Gam^x_yx = x*y
@@ -836,9 +836,9 @@ class :class:`~sage.tensor.modules.comp.Components`; if such
             sage: X.<x,y> = M.chart()
             sage: nab = M.affine_connection('nabla', latex_name=r'\nabla')
             sage: eX = X.frame(); eX
-            Coordinate frame (M, (d/dx,d/dy))
+            Coordinate frame (M, (∂/∂x,∂/∂y))
             sage: nab.add_coef(eX)
-            3-indices components w.r.t. Coordinate frame (M, (d/dx,d/dy))
+            3-indices components w.r.t. Coordinate frame (M, (∂/∂x,∂/∂y))
             sage: nab.add_coef(eX)[1,2,1] = x*y
             sage: nab.display(eX)
             Gam^x_yx = x*y
@@ -848,7 +848,7 @@ class :class:`~sage.tensor.modules.comp.Components`; if such
 
             sage: nab.add_coef()[1,2,1] = x*y
             sage: nab.add_coef()
-            3-indices components w.r.t. Coordinate frame (M, (d/dx,d/dy))
+            3-indices components w.r.t. Coordinate frame (M, (∂/∂x,∂/∂y))
             sage: nab.add_coef()[1,2,1] = x*y
             sage: nab.display()
             Gam^x_yx = x*y
@@ -1457,7 +1457,7 @@ def _common_frame(self, other):
             sage: v = M.vector_field()
             sage: v[:] = [-y, x]
             sage: nab._common_frame(v)
-            Coordinate frame (M, (d/dx,d/dy))
+            Coordinate frame (M, (∂/∂x,∂/∂y))
             sage: e = M.vector_frame('e')
             sage: u = M.vector_field()
             sage: u[e,:] = [-3, 2]
@@ -1773,7 +1773,7 @@ def torsion(self):
             sage: nab.torsion() is t  # a new computation of the torsion has been made
             False
             sage: (nab.torsion() - t).display()
-            (-x - 1) d/dy⊗dx⊗dz + (x + 1) d/dy⊗dz⊗dx
+            (-x - 1) ∂/∂y⊗dx⊗dz + (x + 1) ∂/∂y⊗dz⊗dx
 
         Another example: torsion of some connection on a non-parallelizable
         2-dimensional manifold::
@@ -1925,18 +1925,18 @@ def riemann(self):
             Module T^(1,3)(M) of type-(1,3) tensors fields on the 2-dimensional
              differentiable manifold M
             sage: r.display(eU)
-            (x^2*y - x*y^2) d/dx⊗dx⊗dx⊗dy + (-x^2*y + x*y^2) d/dx⊗dx⊗dy⊗dx + d/dx⊗dy⊗dx⊗dy
-             - d/dx⊗dy⊗dy⊗dx - (x^2 - 1)*y d/dy⊗dx⊗dx⊗dy + (x^2 - 1)*y d/dy⊗dx⊗dy⊗dx
-             + (-x^2*y + x*y^2) d/dy⊗dy⊗dx⊗dy + (x^2*y - x*y^2) d/dy⊗dy⊗dy⊗dx
+            (x^2*y - x*y^2) ∂/∂x⊗dx⊗dx⊗dy + (-x^2*y + x*y^2) ∂/∂x⊗dx⊗dy⊗dx + ∂/∂x⊗dy⊗dx⊗dy
+             - ∂/∂x⊗dy⊗dy⊗dx - (x^2 - 1)*y ∂/∂y⊗dx⊗dx⊗dy + (x^2 - 1)*y ∂/∂y⊗dx⊗dy⊗dx
+             + (-x^2*y + x*y^2) ∂/∂y⊗dy⊗dx⊗dy + (x^2*y - x*y^2) ∂/∂y⊗dy⊗dy⊗dx
             sage: r.display(eV)
-            (1/32*u^3 - 1/32*u*v^2 - 1/32*v^3 + 1/32*(u^2 + 4)*v - 1/8*u - 1/4) d/du⊗du⊗du⊗dv
-             + (-1/32*u^3 + 1/32*u*v^2 + 1/32*v^3 - 1/32*(u^2 + 4)*v + 1/8*u + 1/4) d/du⊗du⊗dv⊗du
-             + (1/32*u^3 - 1/32*u*v^2 + 3/32*v^3 - 1/32*(3*u^2 - 4)*v - 1/8*u + 1/4) d/du⊗dv⊗du⊗dv
-             + (-1/32*u^3 + 1/32*u*v^2 - 3/32*v^3 + 1/32*(3*u^2 - 4)*v + 1/8*u - 1/4) d/du⊗dv⊗dv⊗du
-             + (-1/32*u^3 + 1/32*u*v^2 + 5/32*v^3 - 1/32*(5*u^2 + 4)*v + 1/8*u - 1/4) d/dv⊗du⊗du⊗dv
-             + (1/32*u^3 - 1/32*u*v^2 - 5/32*v^3 + 1/32*(5*u^2 + 4)*v - 1/8*u + 1/4) d/dv⊗du⊗dv⊗du
-             + (-1/32*u^3 + 1/32*u*v^2 + 1/32*v^3 - 1/32*(u^2 + 4)*v + 1/8*u + 1/4) d/dv⊗dv⊗du⊗dv
-             + (1/32*u^3 - 1/32*u*v^2 - 1/32*v^3 + 1/32*(u^2 + 4)*v - 1/8*u - 1/4) d/dv⊗dv⊗dv⊗du
+            (1/32*u^3 - 1/32*u*v^2 - 1/32*v^3 + 1/32*(u^2 + 4)*v - 1/8*u - 1/4) ∂/∂u⊗du⊗du⊗dv
+             + (-1/32*u^3 + 1/32*u*v^2 + 1/32*v^3 - 1/32*(u^2 + 4)*v + 1/8*u + 1/4) ∂/∂u⊗du⊗dv⊗du
+             + (1/32*u^3 - 1/32*u*v^2 + 3/32*v^3 - 1/32*(3*u^2 - 4)*v - 1/8*u + 1/4) ∂/∂u⊗dv⊗du⊗dv
+             + (-1/32*u^3 + 1/32*u*v^2 - 3/32*v^3 + 1/32*(3*u^2 - 4)*v + 1/8*u - 1/4) ∂/∂u⊗dv⊗dv⊗du
+             + (-1/32*u^3 + 1/32*u*v^2 + 5/32*v^3 - 1/32*(5*u^2 + 4)*v + 1/8*u - 1/4) ∂/∂v⊗du⊗du⊗dv
+             + (1/32*u^3 - 1/32*u*v^2 - 5/32*v^3 + 1/32*(5*u^2 + 4)*v - 1/8*u + 1/4) ∂/∂v⊗du⊗dv⊗du
+             + (-1/32*u^3 + 1/32*u*v^2 + 1/32*v^3 - 1/32*(u^2 + 4)*v + 1/8*u + 1/4) ∂/∂v⊗dv⊗du⊗dv
+             + (1/32*u^3 - 1/32*u*v^2 - 1/32*v^3 + 1/32*(u^2 + 4)*v - 1/8*u - 1/4) ∂/∂v⊗dv⊗dv⊗du
 
         The same computation parallelized on 2 cores::
 
@@ -2150,7 +2150,7 @@ def connection_form(self, i, j, frame=None):
 
         Check of the formula `\omega^i_{\ \, j} = \Gamma^i_{\ \, jk} e^k`:
 
-        First on the manifold's default frame (d/dx, d/dy, d:dz)::
+        First on the manifold's default frame (∂/∂x, ∂/∂y, d:dz)::
 
             sage: dx = M.default_frame().coframe() ; dx
             Coordinate coframe (M, (dx,dy,dz))
@@ -2257,7 +2257,7 @@ def torsion_form(self, i, frame=None):
             sage: nab[3,2,1], nab[3,2,2], nab[3,3,3] = x*y+z, z^3 -y^2, x*z^2 - z*y^2
             sage: nab.torsion_form(1)
             2-form torsion (1) of connection nabla w.r.t. Coordinate frame
-             (M, (d/dx,d/dy,d/dz)) on the 3-dimensional differentiable manifold M
+             (M, (∂/∂x,∂/∂y,∂/∂z)) on the 3-dimensional differentiable manifold M
             sage: nab.torsion_form(1)[:]
             [               0             -x^2      (y^2 + y)*z]
             [             x^2                0  x^3 - x^2 + y^2]
@@ -2359,10 +2359,10 @@ def curvature_form(self, i, j, frame=None):
             sage: nab[3,2,1], nab[3,2,2], nab[3,3,3] = x*y+z, z^3 -y^2, x*z^2 - z*y^2
             sage: nab.curvature_form(1,1)  # long time
             2-form curvature (1,1) of connection nabla w.r.t. Coordinate frame
-             (M, (d/dx,d/dy,d/dz)) on the 3-dimensional differentiable manifold M
+             (M, (∂/∂x,∂/∂y,∂/∂z)) on the 3-dimensional differentiable manifold M
             sage: nab.curvature_form(1,1).display()  # long time (if above is skipped)
             curvature (1,1) of connection nabla w.r.t. Coordinate frame
-             (M, (d/dx,d/dy,d/dz)) = (y^2*z^3 + (x*y^3 - x)*z + 2*x) dx∧dy
+             (M, (∂/∂x,∂/∂y,∂/∂z)) = (y^2*z^3 + (x*y^3 - x)*z + 2*x) dx∧dy
               + (x^3*z^2 - x*y) dx∧dz + (x^4*y*z^2 - z) dy∧dz
 
         Curvature 2-forms w.r.t. a non-holonomic frame::
@@ -2371,7 +2371,7 @@ def curvature_form(self, i, j, frame=None):
             sage: ch_basis[1,1], ch_basis[2,2], ch_basis[3,3] = y, z, x
             sage: e = M.default_frame().new_frame(ch_basis, 'e')
             sage: e[1].display(), e[2].display(), e[3].display()
-            (e_1 = y d/dx, e_2 = z d/dy, e_3 = x d/dz)
+            (e_1 = y ∂/∂x, e_2 = z ∂/∂y, e_3 = x ∂/∂z)
             sage: ef = e.coframe()
             sage: ef[1].display(), ef[2].display(), ef[3].display()
             (e^1 = 1/y dx, e^2 = 1/z dy, e^3 = 1/x dz)