1,303 reputation
1022
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location Berkeley, CA
age 24
visits member for 4 years, 1 month
seen Oct 15 at 4:12

I'm a physics student at the University of California.


Aug
4
comment How many positive and even factors does $2013!$ have?
Your last few questions revolve around the number 2013, looks like someone is posting competition questions
Oct
21
comment Construct a function which is continuous in $[1,5]$ but not differentiable at $2, 3, 4$
Took me a minute
Oct
5
comment Common Einstein Notation Identities
@NieldeBeaudrap they weren't meant to be complex examples. For instance working out $A(u)\times A(v)$ where $R$ is 3-by-3 matrix takes a few moments and is something I've encountered a few times.
Sep
9
comment Finding a function's domain from the function's formula
@jorki, you are right, its a little late here so I confused the example in my head with the actual example given in the OP.
Jul
6
comment You see a route 14 bus on the moon. What is the most likely number of bus routes on the moon?
As a school prank you release 3 greased pigs into the school with the numbers 1,2, and 4 painted in bold letters on their backs. What is the most likely number of pigs from the point of view of the school administrator?
Jul
6
comment Prove in full detail that the set is a vector space
@Jyrki I agree and I believe that most reasonable instructors would agree as well. However if this ambiguous wording had come up on an exam I would certainly ask the professor if we are allowed to use any theorem presented in the course. After all, there are much quicker and easier ways to prove that it is a vector space than even the subspace theorem (See Bill Dubuque's answer)
Jul
6
comment Prove in full detail that the set is a vector space
@Virtuoso the key phrase Prove in Full Detail suggests to me that the test wants you to show all the vector space axioms, you might be marked down on an exam if you prove by showing its a subspace.
Jul
6
comment Prove in full detail that the set is a vector space
@Virtuoso Typically you are not allowed to use theorems and concepts that have not been covered up to that point in class. If you are unfamiliar (i.e. it hasn't been covered yet) with the concept of a subspace then you should show all the axioms. Since a subspace is a vector space in its own right, you only need to prove that this set constitutes a subspace of $\mathbb{R}^2$ - it contains 0, closed under addition, and closed under scalar multiplication.
Jul
1
comment Definition of Ring Vs Rng
@Pete the Deskins book (well the dover reprint, I obsessively buy dover reprints for dirt cheap at used book stores) is the one I remember seeing, I was trying to track it down again but @Brian got it before me.
Jun
30
comment Definition of Ring Vs Rng
Didn't really expect to start such debate. I haven't studied enough algebra to see the benefit of using one definition over the other. I didn't realize it was such a contentious issue.
Jun
30
comment Definition of Ring Vs Rng
@Pete I've also encountered some textbooks that state $1\neq0$ as a ring axiom specifically to exclude the trivial ring. Why they do that is beyond me.
Jun
28
comment Examples of results failing in higher dimensions
Proof by pictures still exists in higher math, for example see: en.wikipedia.org/wiki/Commutative_diagram . Although I agree that at the very least there is a rigor behind them.
Jun
28
comment Finding $\csc$ with $\cot$
@Adam trig functions represent relations between the sides of a right triangle. Excepting some corner cases (like $\theta = \frac{\pi}{2}$) you can always construct a right triangle that "represents" the trig relation.
Jun
28
comment Finding $\csc$ with $\cot$
@Adam as I pointed out in my comment, even though you checked 12 times you missed the clear arithmetic error
Jun
28
comment Trig test review
FML is a fairly common adolescent phrase now-a-days, it wasn't meant to be offensive, but I agree it was unnecessary in the question.
Jun
28
comment Finding $\csc$ with $\cot$
You did everthing right, but 9+16 = 25 not 27
Jun
27
comment The mathematics behind Clebsch-Gordan Coefficients
@Theo thanks for that, its what I get for working in a lab with a bunch of Russians - "gord-on"
Jun
24
comment Number of occurrences of the digit 1 in the numbers from 0 to n
While this is a correct way to approach this particular question, the actual problem in question (which is a project Euler problem) requires the sum total of all numbers that satisfy this condition for all digits 1-10. Not so easy (or fast) do with this brute force method (where do you set the upper search limit for instance?).
Jun
24
comment Number of occurrences of the digit 1 in the numbers from 0 to n
This is a not-so-veiled attempt to elicit a solution to a project euler problem.
Jun
4
comment Reason why these two probabilities are equal (Picking Balls in exact order without Replacement)
Intuitively there is a degeneracy between "sublevels" of the same ordering (i.e there are 12 different ways to pick AAABB but they are equivalent). Thus there is nothing special about one ordering versus another, therefore you would expect results that only differ in ordering to have the same probability.