2018-12-10 15:03:37 +0200 received badge ● Famous Question (source) 2018-11-16 14:50:26 +0200 received badge ● Notable Question (source) 2018-01-16 16:44:21 +0200 received badge ● Popular Question (source) 2016-09-12 06:03:40 +0200 received badge ● Notable Question (source) 2016-06-28 16:30:11 +0200 received badge ● Famous Question (source) 2016-06-28 16:30:11 +0200 received badge ● Notable Question (source) 2016-06-28 16:30:11 +0200 received badge ● Popular Question (source) 2016-02-05 01:09:35 +0200 received badge ● Popular Question (source) 2014-01-22 08:57:11 +0200 received badge ● Student (source) 2014-01-22 07:43:46 +0200 asked a question sage-mode in emacs I'm trying to get the syntax highlighting to work in emacs. I have tried to install sage-mode following the manual on the https://bitbucket.org/gvol/sage-mode/... This fail on running the first command: $sage -f sage_mode with error message sage-run received unknown option: -f I use Sage Version 5.9. Could someone help me with this please? 2013-08-30 05:40:04 +0200 commented question Long expression in printed-out documents I have the same problem. My equations are way too long to be shown on one line in pdf file. I have tried to export it to LaTeX and split manually, but it is not an easy job to do. Have you found any solution for that? 2013-08-20 07:06:15 +0200 commented answer vector derivative returns a scalar Anyway, I reckon that the first example is probably a bug. The derivative of n-dimensional vector should have n-dimensions again no matter to which ring it belongs to. Would you know how to report that, please? 2013-08-20 06:57:21 +0200 marked best answer vector derivative returns a scalar Look at the help of derivative. It works on symbolic functions, polynomials, and symbolic expressions. Your variable u is not a function, so it is not really being considered a two dimensional symbolic expression or function. If you do sage: u(x,y) = matrix(1,2,[-1,1]) sage: derivative(u, x) (x, y) |--> 0  then you can see that it is considering it as a two dimensional function. In the second case, you have a function of one variable in the variable x. The alternative fix is to work in the symbolic ring: sage: u = matrix(SR, [-1,1]) sage: derivative(u,x) [0 0]  2013-08-20 06:57:21 +0200 received badge ● Scholar (source) 2013-08-20 06:56:47 +0200 commented answer vector derivative returns a scalar Thanks, the fix with a symbolic ring is helpful. In my problem the$\vec{u}$really is a function, just happens to be a constant at this occasion. 2013-08-19 12:45:42 +0200 commented question vector derivative returns a scalar Compared to: a(x) = function('a',x) b(x) = function('b',x) u = matrix(1,2,[a,b]) r = derivative(u,x);r Which gives a vector as expected: [x |--> D[0](a)(x) x |--> D[0](b)(x)] 2013-08-19 12:38:26 +0200 asked a question vector derivative returns a scalar Trying to obtain the derivative of$\vec{u} = [-1,1]$using the following code: u = matrix(1,2,[-1, 1]) r = derivative(u,x); r I get a scalar value 0. Although according the following relation it should be a 2-dimensional zero vector. $$\frac{\mathrm{d} \vec{u}}{\mathrm{d} x} =\frac{\mathrm{d}}{\mathrm{d} x} [-1, 1] = [ \frac{\mathrm{d}}{\mathrm{d} x}(-1), \frac{\mathrm{d}}{\mathrm{d} x}(1) ] = [0, 0]$$ Why does it happen? In the case it's a bug where could I report it? Thanks 2013-08-15 10:10:02 +0200 received badge ● Self-Learner (source) 2013-08-15 10:10:02 +0200 received badge ● Teacher (source) 2013-08-15 08:36:41 +0200 answered a question append a variable to a vector So an solution which work is to convert the vector to a list, append the new variable and convert to a vector again. The code for that would be as follows: u = x.list() u.append(sigma) u = vector(u) Do you see any potential problems with this solution? Why there is no method append in vector? Could I do better? 2013-08-15 08:07:50 +0200 received badge ● Supporter (source) 2013-08-15 06:26:48 +0200 received badge ● Editor (source) 2013-08-15 06:23:40 +0200 asked a question append a variable to a vector I would like to define a new vector in Sage$\vec{u} = [O, P, \sigma]$using a previously defined vecotor$\vec{x} = [O, P]$and a new variable$\sigma$. My code looks like: var(O, P'); var('sigma'); x = vector([O,P]); u = vector([x, sigma]); Which gives an error: TypeError: unable to find a common ring for all elements Apparently this is because vector() requires the variables to be of the same ring. In my case x.parent() Vector space of dimension 2 over Symbolic Ring and sigma.parent() Symbolic Ring There is any way how to connect this two objects ($\vec{x}$,$\sigma\$) together to create one vector?