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20150727 10:39:17 +0200  asked a question  imports in sage/combinat/free_module.py I was reading the code in and then in the fourth line there is and later on we find Why is this so? Can't some of these lines be erased? 
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20150301 16:25:01 +0200  answered a question  quaternionvalued differential forms This seems to work fine: 
20150228 21:44:34 +0200  commented question  substitute x*y by u It doesn't look like there's support for substituting products. Instead you can do 
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20150226 06:44:08 +0200  asked a question  quaternionvalued differential forms I'm trying to define quaternionvalued differential forms in Sage. For example, take $e_0$, $e_1$, $e_2$, $e_3$ to be the quaternion generators and $d x^0$, $d x^1$, $d x^2$, $d x^3$ be the generators of the exterior algebra. So for example I'd like to be able to compute $d X \wedge d X^\dagger$, where $d X = e_0 d x^0 + e_1 d x^1 + e_2 d x^2 + e_3 d x^3$, $d X^\dagger = e_0 d x^0  e_1 d x^1  e_2 d x^2  e_3 d x^3$. Edit: I tried taking a tensor product between an exterior algebra and a quaternion algebra 
20150226 06:37:16 +0200  commented answer  Incorrect parsing of docstring of sage.structure.indexed_generators.IndexedGenerators @kcrisman, I don't have a Trac account yet, I should probably get one. I did find another instance of this problem in the documentation of 
20150219 10:34:08 +0200  commented answer  Incorrect parsing of docstring of sage.structure.indexed_generators.IndexedGenerators Another such issues appear for 
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20150214 14:54:41 +0200  commented answer  Incorrect parsing of docstring of sage.structure.indexed_generators.IndexedGenerators I noticed another similar (related?) issue in the help for the where some 
20150207 10:28:31 +0200  asked a question  Incorrect parsing of docstring of sage.structure.indexed_generators.IndexedGenerators [This is more of a bug report, but I'm not sure how to report bugs.] I'm running 'Sage Version 6.5.rc0, Release Date: 20150129' and when I display the help for 
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20150115 08:46:04 +0200  commented answer  Transpose of a column vector Sage is written in the Python language. Python is an objectoriented programming language. You can think of an object as a way to store some data together with functions which operate on it an modify it. Everything in Python is an object; numbers are objects, lists are objects, etc. List is a very basic object which does not support many operations; you can index a list, you can join two lists, and you can do a few other things. Matrix is an object which supports many more operations. For example, you can compute the Jordan form of a matrix, you can multiply two matrices of appropriate sizes, etc. So a object of type Matrix corresponds better to the abstract mathematical notion of matrix than does an object of type list. 
20150115 08:40:14 +0200  answered a question  what does ratpoly.<t> = PolynomialRing(QQ) mean Sage does some preparsing on what you type. You can see what happens with the command 
20150114 06:50:16 +0200  commented answer  why don't sage return exact value in some functions @Chong Wang: Here you are in the situation where you already know the answer to a problem and you want the computer to show it to you in the exact form you had in mind. This rarely works and most often leads to frustration. A way out of frustration is to understand the reasons why the computer produced the answer you don't like. In the factorization above \sqrt(2) and 1.414213562373095? are equally valid names for the same number except that the second one is more general. The first one only applies for the rare numbers which can be written in terms of radicals. 
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20150114 06:24:46 +0200  answered a question  why don't sage return exact value in some functions The first thing to realize is that the form the factorization should take depends on the base field for the polynomial. The classical example is the polynomial x^2+1. It can be factorized as (x+i)(xi) but only over the complex numbers. It seems that most of the symbolic mathematics software chooses to work over the real numbers and does not factorize x^2+1. This is of course an arbitrary choice and is not what Sage is doing. This is one reason why you must specify a base field when defining a polynomial. In your case, the answer is not exact because the field RR is not exact. Here's what the documentation for RR (obtainable by typing RR?) says:
Instead of using RR, you could use the algebraic numbers QQbar. Notice the question mark in the decimal expansion. It indicates that the expansion continues but since it may be very long or infinite can not be fully displayed. I'm not completely sure how to make Sage show the output you would like to get, but of course this is only going to work in simple situations where the roots of the polynomials can be written using radicals. The vast majority of algebraic numbers are not of this type. Maybe Sage should have a field of numbers which can be written using radicals, then you could factor your polynomial over that field which, it seems to me, is what you would like to get. It seems to me like this might be a good field to have, but it doesn't seem to be implemented at this point. 
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20150112 23:42:17 +0200  answered a question  Transpose of a column vector Note that you are trying to multiply a matrix by a list. Instead of using a list you should use another matrix. Here's a way you can do it: Note several things

20141210 07:20:00 +0200  commented question  tab completion for mathematica fails OK, I forgot to mention that I'm using version 10 of Mathematica. Are you using the same version? It could be that something broke starting with version 10... 
20141209 23:05:06 +0200  asked a question  tab completion for mathematica fails Hello, In sage 5.6 if I type mathematica and then TAB, the program hangs. I think it's probably waiting for some input from Mathematica. I can see that a Mathematica process is started. For Maple, the TAB completion works well. Can you confirm this? I'm using 'Sage Version 6.5.beta2, Release Date: 20141204' 
20141126 10:09:07 +0200  commented question  How does one graph this? You can try plotting separately and then combine 
20140922 19:04:32 +0200  commented question  Difficulties with resultants and Tschirnhaus transformations If I declare variables, then solve also works sage: a, b = var('a b') sage: solve([rc[2],rc[3]],[a,b]) [[a == (11/7), b == (2/7)], [a == 3, b == 0]] 
20140922 14:07:45 +0200  asked a question  pattern matching Is it possible to use pattern matching in Sage? I have some experience with Mathematica and I'm currently thinking about switching, and I'm evaluating what Sage can do. As far as I can see pattern matching is not supported. Is this true? If yes, are there any plans to support it in the future? See here for some examples. 