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2016-08-05 21:03:59 +0200 | commented answer | How can I override the __call__ method of a matrix Ok, after thinking about it, I realise that this isn't quite what I want. The whole point of using Matrix is I don't have to commit to (or even think about) the base field or ring - the initialisation procedure for Matrix takes care of that for me. |

2016-08-05 20:17:59 +0200 | answered a question | Forming a polytope from only its combinatorial data If by "visualize" you mean "give a geometric realization of" then I think that the answer should be "no" as I rather suspect that there are high-dimensional combinatorial polytopes that have no geometric realization. Even for three-dimensional polytopes the realization problem is delicate - there are even several layout algorithms for planar graphs. (There is at least one such implemented in sage - see: http --- fix --- doc.sagemath.org/html/en/reference/plotting/sage/graphs/graph_plot.html ). On the other hand, if you want to see the face poset in a graphical way, this is much easier. For example see this post: https --- fix --- sheaves.github.io/Subgroup-Lattice/ and pay attention to the "plot" method of a Poset. |

2016-08-05 19:52:51 +0200 | commented answer | canonicalize_radical for matrices. In the end, I went with because it feels a bit more "pythonic". I suppose what I really want is to be told how to make a feature request. I'll add that to the original question. |

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2016-08-05 19:48:34 +0200 | commented question | How can I override the __call__ method of a matrix Ok, I understand that Matrix is a metaclass, not a class. But I really want the functionality of Matrix, not some special case. In my particular usecase I don't know how the matrix will be given. I just know that the __init__ that comes with Matrix can handle the input. For example - what if the input has entries in some number field? Those are not integers... |

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2016-08-03 23:25:40 +0200 | commented answer | How can I override the __call__ method of a matrix Ok, I see that perhaps I can't use the same __init__ method, as I want a MyMatrix, not a Matrix. But we haven't gotten there yet - my toy example throws an error on the first line, not when I try to use it. I'll add the error message to the post. Regarding the call that is already implemented - it is exactly that method which I wish to override. |

2016-08-03 23:21:31 +0200 | commented answer | How can I override the __call__ method of a matrix Neat - thanks for this. |

2016-08-02 22:14:55 +0200 | commented answer | canonicalize_radical for matrices. Yes, I know that I can write some code to do want I want (and I have done so!). However, as my question states, I am asking for a feature to be implemented - namely the simplify methods should work the same for "scalars", "vectors", and "matrices". In any case, thank you for the reply. |

2016-08-02 20:46:22 +0200 | asked a question | canonicalize_radical for matrices. The following all works However the following doesn't work: EDIT: Could somebody please tell me the right place to ask for "vectorization of canonicalize_radical for matrices" as a new feature of sage? |

2016-08-02 20:35:48 +0200 | commented answer | How can I override the __call__ method of a matrix Yes, I see that. But there should be a way to define a new class (or new metaclass) that inherits from matrix and does what I want? |

2016-08-02 20:33:36 +0200 | commented question | How to make matrices act like linear operators (ie like functions)? Thanks - the webpage was being slow... |

2016-08-02 20:06:29 +0200 | asked a question | How to make matrices act like linear operators (ie like functions)? I'd like to override the __call__ method of a matrix so that M(v) returns M*v. That is, I'd like to use functional notation (to maintain compatibility with a pre-existing body of code). So I tried the following: but this doesn't work because Matrix is a MatrixFactory (?) ie it is a metaclass, not a class. I don't know anything about metaclasses, so, after banging my head against various walls, I am asking here. |

2016-08-02 20:06:29 +0200 | asked a question | How can I override the __call__ method of a matrix I'd like to override the __call__ method of a matrix so that M(v) returns M*v. That is, I'd like to use functional notation. So I tried the following: but this doesn't work. Here is the error message I get when I try the above code in sage: I don't know anything about metaclasses. After banging my head against various walls, trying to learn, I am asking here. |

2015-09-09 03:26:07 +0200 | commented answer | How to use linear algebra inside of MixedIntegerLinearPrograms? Thanks for finding a partial solution, and for the reference to linear_program. I'll take a look. |

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2015-09-07 04:41:48 +0200 | asked a question | How to use linear algebra inside of MixedIntegerLinearPrograms? I have a largish matrix M that defines a polytope P, via a bunch of constraints of the form u.v > b. Here u is the vector of variables and v ranges over the columns of the matrix M. I want to optimize a simple linear functional over P. I can use a MixedIntegerLinearProgram to solve this problem. But I have to roll my own dot_prod function, because sage will not let me treat u as a vector. Is there something I've missed? Here is the code - |

2015-09-07 04:23:14 +0200 | commented answer | Why do I get the "unable to find a common ring for all elements" error message? Basically, you are reimplementing the dot product. That seems like a "bad thing". Obviously linear algebra and linear programming should play well together - can this actually be done? |

2013-12-18 12:35:36 +0200 | answered a question | Does Sage "Show Its Work"? I think that http://ask.sagemath.org/question/474/... has the answer to your question, which unfortunately is "no". You should consider asking the sage developers this question. Note that there are various sites on-line that offer homework help. The first that springs to mind is http://math.stackexchange.com/ which states "Mathematics Stack Exchange is a question and answer site for people studying math at any level". |

2013-12-17 17:56:53 +0200 | commented answer | Does Sage "Show Its Work"? For example, Wolfram Alpha can do something like this - see http://blog.wolframalpha.com/2012/09/26/introducing-expanded-step-by-step-math-solutions/ I'll note that the one time I tried to use this feature, WA fell over. :) |

2013-12-17 17:53:58 +0200 | commented answer | Does Sage "Show Its Work"? I think the questioner is asking "Can I see the steps whereby sage arrived at this answer?" This is not very well-defined, but in some cases, "showing steps" would be a useful feature. |

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