Reputation
16,719
Top tag
Next privilege 20,000 Rep.
Access 'trusted user' tools
Badges
5 25 60
Newest
 Populist
Impact
~72k people reached

49m
comment Is there a notation for saying that a function is defined on some subset of a set?
Often written as $f : D \subset X \to Y$
Aug
31
comment Manifolds with a finite but not trivial fundamental group
Small question about notation. When I was coming up through undergraduate algebra in Australia we would preferentially write $\mathbb Z_n$ over $\mathbb Z/n\mathbb Z$. While typically MSE users write the latter, longer form. Is there any important reason for this, or perhaps just a slightly different standard in the U.S.?
Aug
28
comment Is it right to say that if two vectors, $A$ and $B$, have same $L^p$ norms, for all $p$, then $A = B$?
(By the way, writing "$L^p$ norms" and then talking about components is confusing. The $L^p$ spaces are well defined vector spaces of functions with a specific norm. Because you are talking about components, I take it you actually mean the $\| \cdot \|_p$ norm applied to the vector spaces $\mathbb R^n$.)
Aug
28
comment Is it right to say that if two vectors, $A$ and $B$, have same $L^p$ norms, for all $p$, then $A = B$?
Then don't we have $\|(1,2)\|_p = \|(2,1)\|_p$ for all norms $\| \cdot \|_p$ on $\mathbb R^2$?
Aug
27
reviewed Approve Solving Differential Equation $\frac{dy}{dx} = 1 -\sin(x+y)/(\sin y \cos x)$ by separating variables
Aug
27
comment Solving Differential Equation $\frac{dy}{dx} = 1 -\sin(x+y)/(\sin y \cos x)$ by separating variables
Did you try simplifying?
Aug
27
answered Is $\sin( | z^{2}| )$ ,where z is complex, analytic?
Aug
26
revised Evaluate $\int \theta\sec\theta \tan\theta \ d\theta$
added 24 characters in body; edited title
Aug
23
reviewed Approve Solving $\cos^2{\theta}-\sin{\theta} = 1$
Aug
23
revised If $\left\langle b,c\right\rangle =\left\langle c,a\right\rangle=\langle a,b\times c\rangle =\dfrac {1} {2}$, find $\left\langle a,b\right\rangle$.
edited title
Aug
22
comment How to go about proving that $\cos(\frac{\pi}{2}-x) = \sin(x)$?
It depends where you start and level of rigour required. If you have this identity, it's straight forward to show formally: $\cos(a + b) = \cos a \cos b - \sin a \sin b$. But I think an intuitive approach going back to the unit circle is more instructive.
Aug
22
reviewed Leave Open An isomorphism between two Banach algebras
Aug
22
reviewed Looks OK Prove $a|b \wedge b|a \implies a=\pm b$
Aug
22
reviewed Approve A certain partial derivative
Aug
21
comment Is |AxBxC| = |Ax(BxC)|?
Is there a bijection between the two sets? (Yes.)
Aug
21
comment Derivative of a logarithm from first principles
(The $\mathbb d$ and $\mathbb e$ are over the top.)
Aug
21
revised Derivative of a logarithm from first principles
rolled back to a previous revision
Aug
21
revised Derivative of a logarithm from first principles
rolled back to a previous revision
Aug
19
comment How many different dice exist? That is, how many ways can you make distinct dice that cannot be rotated to show they are the same?
I have rolled back your question to its original form, as for as long as it exists on Maths SE, it might as well be useful to others. If you want to delete the question, you can do that yourself.
Aug
19
revised How many different dice exist? That is, how many ways can you make distinct dice that cannot be rotated to show they are the same?
rolled back to a previous revision