2020-07-26 13:13:44 +0200 commented question Reduction to a rational expression Yeah, homework. A generic ring is a ring over the rationals. But I don't see why the ring itself is relevant, the answer could be written as a function of some elements of the ring. They don't have to be specified. 2020-07-25 00:01:14 +0200 received badge ● Student (source) 2020-07-24 19:13:46 +0200 received badge ● Editor (source) 2020-07-24 19:12:44 +0200 asked a question Reduction to a rational expression I have the the following expression: $tan(m \cdot actan(x) + n \cdot arctan(y))$ For what values of $n,m \in \mathbb{N}$ is this expression reducible to a rational expression in $R[x,y]$, where $R$ is a generic ring? Is there some rule $lhs => rhs$ that is needed in order to get a rational expression form the expression above? 2020-05-28 12:15:35 +0200 commented answer what is the equivalent function of mathematica's FullForm in Sage? If you use the FullForm function in Mathematica, for example on the matrix {{1, 1},{2, 3}} you will get: List[List[1,1],List[2,3]] 2020-05-28 12:13:11 +0200 commented answer what is the equivalent function of mathematica's FullForm in Sage? I have a homework assignment, where i'm asked to find how certain objects (e.g. matrices) are represented in a CAS. The question is of course a general question and can be solved in other CASs, but since i'm already comfortable with Sage i tried to solve this question using Sage. To make the question clear i will give an example for the internal structure of x - y + z, where x,y,z are all variables, i.e var(x y z). etb = ExpressionTreeBuilder(vars=('x','y','z') x = etb.var('x') y = etb.var('y') z = etb.var('z') v = x - y + z print(v)  for this code you get something like: add(sub(v_0,v_1),v_2). This shows how a symbolic expression like x -y +z is represented in Sage, and i'm trying to do the same for matrices, but it did not work so far. 2020-05-28 01:26:04 +0200 asked a question what is the equivalent function of mathematica's FullForm in Sage? i'm trying to find the internal representation of matrices in sage. In Mathematica we can simply use FullForm, and this will show that matrices are internally lists in Mathematica. But i could not find any function that does the same in Sage!