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Jul
6
comment How many times can you round a number?
This doesn't answer the question. The question is about how many iterations it takes for a particular rounding algorithm to terminate.
Jul
5
answered Permutations of Objects on Grid
Jul
5
revised Permutations of Objects on Grid
edited tags
Jul
5
comment Bijection from $\mathbb{R}^n$ to $\mathbb{R}$ that preserves lexicographic order?
This is definitely not abstract algebra. I'd be tempted to tag it as topology, but I'm not sure.
Jul
5
comment Why is this proof of $\mathbb{N}\times\mathbb{N}$ being countable not formal?
Rigor is not a rigorously defined notion. It's a spectrum.
Jul
5
answered Does cofactor expansion generalize to complex matrices?
Jul
5
accepted History of $p$-adic numbers
Jul
5
comment How to distinguish walking on a sphere or on a torus?
To be more systematic, get a partner and a rope eash and walk out from the same starting point at right angles to one another, always in a straight line. If you're on a torus, both of you will return home, but one of you won't be able to contract the rope.
Jul
5
comment Additive non-abelian group?
@user139981 Yes, typically denoted by $x^n$ in the general case.
Jul
4
revised Understanding matrices.
added 445 characters in body
Jul
4
revised Understanding matrices.
added 163 characters in body
Jul
4
revised Understanding matrices.
added 809 characters in body
Jul
4
answered Understanding matrices.
Jul
4
comment Meaning of the characteristic polynomial of a matroid
I'm not sure your interpretation of the characteristic polynomial of a matrix, in the last paragraph, is really all that profound. What do you mean by "how close"?
Jul
4
comment Describing a partition for an equivalence relation?
Are you sure that's not $x,y\in\mathbb R$?
Jul
4
comment I'm forgetting maths..
Your question doesn't really have enough detail to be answerable. What are you forgetting? How long does it take you to forget it? And why does the obvious solution (go back and refresh your memory) not work?
Jul
3
comment If $foo=f(x,\dot{x})$, what are $\frac{\partial f}{\partial \dot{x}}$ and $\frac{\partial f}{\partial x}$?
@MisterMystère Like I said, I don't think "independent" means anything. $f$ is a function of two variables, so it makes sense to speak about its first or second partial derivatives. It also makes sense to compose those with the functions $x$ and $x'$.
Jul
3
comment If $foo=f(x,\dot{x})$, what are $\frac{\partial f}{\partial \dot{x}}$ and $\frac{\partial f}{\partial x}$?
@MisterMystère I don't think "independent variable" (or indeed "variable") has any meaning in mathematics.
Jul
3
answered If $foo=f(x,\dot{x})$, what are $\frac{\partial f}{\partial \dot{x}}$ and $\frac{\partial f}{\partial x}$?
Jul
2
answered The image of a basis under an onto linear transformation is a basis