2021-05-09 22:12:29 +0200 | commented question | Geodesics/tangent vector evaluation interpolation error Since you are dealing with a single chart, why don't you use the method solve() instead of solve_accross_charts() and re |

2021-05-09 18:07:40 +0200 | commented question | Geodesics/tangent vector evaluation interpolation error The code is still incomplete; m is not defined and the metric is not initialized. |

2021-05-09 12:16:01 +0200 | commented question | Geodesics/tangent vector evaluation interpolation error Can you share the whole code that you are using, so that one can reproduce your issue? In particular, what are M and ini |

2021-05-05 17:24:36 +0200 | answered a question | Gaussian Curvature of a 2D manifold. For 2-dimensional Riemannian manifolds, the Gaussian curvature is obtained as half the Ricci scalar: K = M.metric().ric |

2021-05-04 16:26:19 +0200 | received badge | ● Nice Answer (source) |

2021-05-02 23:22:10 +0200 | received badge | ● Nice Answer (source) |

2021-05-02 21:59:27 +0200 | answered a question | Integrating differential forms Indeed, integration of differential forms is not implemented yet. Meanwhile, you can pass the symbolic expression repres |

2021-05-01 15:24:09 +0200 | edited answer | Working with tetrads and the spin connection Spin connections are not implemented yet. However, note that generic tetrads are implemented and that the connection coe |

2021-05-01 15:14:02 +0200 | answered a question | Working with tetrads and the spin connection Spin connections are not implemented yet. However, note that generic tetrads are implemented and that the connection coe |

2021-04-29 00:12:46 +0200 | edited answer | Differential forms on non-standard spherical coordinates Simply use the method chart to define your own version of spherical coordinates and then relate them to Sage's default s |

2021-04-29 00:11:31 +0200 | edited answer | Differential forms on non-standard spherical coordinates Simply use the method chart to define your own version of spherical coordinates and then relate them to Sage's default s |

2021-04-28 23:03:48 +0200 | commented answer | Differential forms on non-standard spherical coordinates It looks correct to me: in the coordinate basis dr/\dtheta/\dphi there should not be any scaling factor like 1/(r*cos(th |

2021-04-28 22:57:20 +0200 | edited answer | Differential forms on non-standard spherical coordinates Simply use the method chart to define your own version of spherical coordinates and then relate them to Sage's default s |

2021-04-28 22:55:32 +0200 | edited answer | Differential forms on non-standard spherical coordinates |

2021-04-28 18:23:29 +0200 | commented answer | Differential forms on non-standard spherical coordinates It looks correct to me: in the coordinate basis dr/\dtheta/\dphi there should not be any scaling factor like 1/(r*cos(th |

2021-04-28 15:35:19 +0200 | received badge | ● Nice Answer (source) |

2021-04-28 11:46:44 +0200 | answered a question | Background for plot should include axes and labels This answers only the question about the font size: use the option axes_labels_size in plot() to set the relative size b |

2021-04-28 11:28:15 +0200 | edited answer | Differential forms on non-standard spherical coordinates |

2021-04-28 10:50:49 +0200 | answered a question | Differential forms on non-standard spherical coordinates |

2021-04-15 21:51:03 +0200 | edited answer | Why `unable to convert (sin(h(x)), cos(h(x))) to a symbolic expression`? Following @slelievre 's comment, here is a possible answer using maps $\mathbb{R} \to \mathbb{R}^2$ and $\mathbb{R}\to\m |

2021-04-15 21:47:57 +0200 | edited answer | Why `unable to convert (sin(h(x)), cos(h(x))) to a symbolic expression`? Following @slelievre 's comment, here is a possible answer using maps $\mathbb{R} \to \mathbb{R}^2$ and $\mathbb{R}\to\m |

2021-04-15 18:14:14 +0200 | received badge | ● Necromancer (source) |

2021-04-15 13:23:06 +0200 | answered a question | Why `unable to convert (sin(h(x)), cos(h(x))) to a symbolic expression`? Following @slelievre 's comment, here is a possible answer using maps $\mathbb{R} \to \mathbb{R}^2$ and $\mathbb{R}\to\m |

2021-04-12 11:03:54 +0200 | commented answer | How can I define a submanifold-with-boundary of a Euclidean space in Sage? There is already a ticket for manifolds with boundaries: Trac 30080, so they might be implemented soon. |

2021-04-08 10:03:23 +0200 | answered a question | Is there a way to define a submanifold of a Euclidean space by providing a list of implicit constraints, instead of by declaring a separate manifold and explicitly defining the embedding? This is not implemented yet. The current functionalities for submanifolds are described in [1], [2], [3], [4] and [5]. |

2021-04-08 09:55:39 +0200 | answered a question | Is there a built-in way to integrate a vector or differential form field on an embedded submanifold of Euclidean space? Sorry, integration on manifolds is not implemented yet. You are very welcome to contribute to SageMath by implementing i |

2021-04-08 09:51:19 +0200 | answered a question | How can I define a submanifold-with-boundary of a Euclidean space in Sage? Sorry, manifolds with boundary are not implemented yet. If you would like to implement them in SageMath, please visit ht |

2021-04-05 11:14:01 +0200 | commented question | Evaluating a form field at a point on vectors Motivated by your question, I've opened the ticket https://trac.sagemath.org/ticket/31609 to add a method vector() in or |

2021-04-05 11:13:01 +0200 | commented question | Evaluating a form field at a point on vectors Motivated by your question, I've opened the ticket https://trac.sagemath.org/ticket/31606 to add a method vector() in or |

2021-04-02 21:30:20 +0200 | commented answer | Coordinate charts, functions of one coordinate as bounds of another(?) Could you provide a concrete example of your function r(th)? X.add_restrictions(r>R(th)) should work for any function |

2021-04-02 19:28:15 +0200 | answered a question | Coordinate charts, functions of one coordinate as bounds of another(?) Use the chart method add_restrictions (type X.add_restrictions? for the documentation). On your example, this gives: sa |

2021-04-02 01:57:22 +0200 | received badge | ● Good Answer (source) |

2021-02-28 10:13:33 +0200 | commented question | Ask Sagemath has a new home ! Thank you Thierry! |

2021-02-26 14:12:17 +0200 | answered a question | Differential forms and chain rule Building on @Emmanuel_Charpentier's comment, the closest thing you can do to use the chain rule with unspecified differential forms is something like But as you can see, all computations use the underlying coordinates (x,y), even in assessing coordinate-free statements like in |

2021-02-07 14:24:51 +0200 | answered a question | Divergence of inverse square In the current implementation, vector fields are assumed to be smooth functions on their domain. The vector field that you have defined is not (actually, it is not even defined at $r=0$), so I would say this is not a bug. |

2021-02-07 11:33:25 +0200 | answered a question | vector_field.apply_map before and after vector.display (weird behaviour) Well, I would say that this is caused by a somewhat strange operation that you are asking for. When you write you are initializing the vector field with components in the frame Then everything is OK. |

2021-02-03 15:19:52 +0200 | received badge | ● Nice Answer (source) |

2021-02-02 08:59:18 +0200 | answered a question | Displaying all symbolic expression with ExpressionNice No, unfortunately it is not possible to make it the default for all symbolic expressions. |

2021-02-02 08:50:57 +0200 | answered a question | latex_name and derivatives in sagemanifolds I cannot reproduce the issue with Sage 9.2. Typing the following code in a Jupyter notebook yields $\frac{\partial\,L}{\partial \left( \dot{q}_1\left(t\right) \right)} \frac{\partial\dot{q}_1}{\partial t} \mathrm{d} t$ |

2021-02-01 15:41:48 +0200 | commented answer | subs in vector field Yes this is a bug! I was not aware that the method |

2021-02-01 08:07:05 +0200 | answered a question | subs in vector field You have to use the method See the documentation of apply_map() for more details. |

2021-02-01 00:13:08 +0200 | answered a question | Why doesn't Sage return `True` for `e < 3`? You have to enforce the check of the inequality by asking for a Boolean: |

2021-01-30 12:48:11 +0200 | commented question | Functions with operation (multiplication) as argument I don't understand your question; |

2021-01-30 12:27:46 +0200 | answered a question | 2 sets of coordinates in EuclideanSpace? In But you can define as many charts as you want by means of the method To complete the construction, you have to specify the transition map from previously defined coordinates: as well as its inverse, either by asking Sage to compute it (method Then Sage can compute vector field components in the new coordinate frame: For more details, see the coordinate chart documentation. |

2021-01-29 10:43:08 +0200 | answered a question | Matrix multiplication with a vector in EuclideanSpace You have to convert the matrix Here is the full example: Note that the action of the endomorphism Note also that if the matrix |

2021-01-27 19:41:08 +0200 | commented question | Extracting numerator of a Ricci tensor component See the answer to question 55475 |

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