# Search results

1. ### The most beautiful chain of equalities I have ever seen

I was doing some basic analysis of the Dedekind eta function and some Dirichlet series and the following equality just fell out: \sum_{k=1}^\infty\frac{\mu (k)-\varphi (k)}{k}\log \left( 1-\frac{1}{\phi^k} \right) = \prod_{k=1}^\infty \left( 1-\frac{1}{\phi^k} \right)^{2\pi i\frac{\mu...
2. ### Equality of definite integrals, relation between integrands

Suppose we are given two functions: f:\mathbb R \times \mathbb C \rightarrow\mathbb C g:\mathbb R \times \mathbb C \rightarrow\mathbb C and the equation relating the Stieltjes Integrals \int_a^\infty f(x,z)d\sigma(x)=\int_a^\infty g(x,z)d\rho(x) where a is some real number, the...
3. ### Gamma Function and the Euler-Mascheroni Constant

The so called product integral was developed in 1887 by Volterra according to http://en.wikipedia.org/wiki/Product_integral And here is the page for multiplicative calculus, just in case anyone is interested: http://en.wikipedia.org/wiki/Multiplicative_calculus
4. ### Gamma Function and the Euler-Mascheroni Constant

Just in case anyone wanted to know, I found a lot about it. It's called Bigeometric (or Multiplicative) Calculus.
5. ### Gamma Function and the Euler-Mascheroni Constant

Yea I think so too. This is a little bit off topic, but, it was also my reason for looking at the properties of the gamma function. Have you seen any theory on extending a product over a continuous interval, as is done with the sum to create the integral? I have tried to develop an approach...
6. ### Gamma Function and the Euler-Mascheroni Constant

Actually, it follows immediately if you change the LHS of the last line to the equivalent -(log(gamma(1+s))-log(gamma(1))/s since log(gamma(1))=log(1)=0 and the digamma function ψ is defined to be the logarithmic derivative of the gamma function, so that under the limit as s ->0 this is...
7. ### Gamma Function and the Euler-Mascheroni Constant

I didn't even think to look at digamma, but it seems that as usual, you are indeed correct. It follows straight from a series representation for it. Basically, the last line in my analysis is almost exactly this ψ(x+1)=-γ+∑(1/k-1/(x+k))
8. ### Gamma Function and the Euler-Mascheroni Constant

I was taking a break from studying from my real analysis, electrodynamics, and nuclear physics exams this week, and, being a math-phile, I decided to play around with the gamma-function for some reason. Anyway, I used the common product expansion of the multiplicative inverse, and I arrived at a...
9. ### Does Cayley's Theorem imply all groups are countable?

Note that under union with 0 this is in fact a group, if x is in G and y is in R and |x-y|<epsilon then x is equivalent to y if you consider y to be an element of G. In other words, once you set the precision, to consider such a y as an element of G also, the part of y that is smaller than...
10. ### Does Cayley's Theorem imply all groups are countable?

What I'm saying for the real numbers, is that every time you try to fix some labeling of them, there exist some elements in the real line not in this labeling. How then can a transitive action, which just means that the action has a single orbit containing all permutations of the group, be defined?
11. ### Does Cayley's Theorem imply all groups are countable?

I understand that it may be infinite. But i just don't see how it is possible to have a group acting on itself transitively if it is uncountable. If it's uncountable it can't be indexed by any subset of the natural numbers, so a set of permutations which permutes every element to every other...
12. ### Does Cayley's Theorem imply all groups are countable?

I meant union with 0.
13. ### Does Cayley's Theorem imply all groups are countable?

My question is exactly what is stated in the title: Does Cayley's theorem imply that all groups are countable? I don't see how a well defined transitive action of an uncountable group on itself. How could you possibly find a set of permutations sending a single element to every other element in...
14. ### Consequence of the First isomorphism theorem

If n is the order of G, Aut(G) is isomorphic to the symmetric group on n letters. It's order is n!. A quotient of G by some normal subgroup is less than or equal to the order of G. Say, the order G/Z(G) is m. Then m<=n. How can this quotient possibly be of order n! unless n is less than or equal...
15. ### Question about normal subgroups/Lattice Isomorphism Theorem

I was just brushing up on some Algebra for the past couple of days. I realize that the lattice isomorphism theorem deals with the collection of subgroups of a group containing a normal subgroup of G. Now, in general, if N is a normal subgroup of G, all of the subgroups of larger order than N do...
16. ### Uniform convergence of a product of functions

I was actually thinking that I could show that (f_n - f)g is continuous, on the interval for all n since f is bounded on [a,b] and f_n is bounded for all n on [a,b]. That still doesn't use the endpoints though, which I'm figuring are key. I do understand what you are saying though, I was trying...
17. ### Uniform convergence of a product of functions

Homework Statement Let \left[a,b\right] be a closed bounded interval, f : [a,b] \rightarrow \textbf{R} be bounded, and let g : [a,b] \rightarrow \textbf{R} be continuous with g\left(a\right)=g\left(b\right)=0. Let f_{n} be a uniformly bounded sequence of functions on \left[a,b\right]. Prove...
18. ### How to derive beta function as pochhammer contour integral?

Awesome, thanks. I haven't used mathematica in a few years. Actually, last time I used mathematica I don't even think I knew what a contour was. I have been using python lately to do everything computationally/graphically. It would be awesome though to not have to literally write my own program...
19. ### The space of solutions of the classical wave equation

No, he's right. Every solution is of that functional form. Every solution to the wave equation has a forward traveling wave and a backward traveling wave. However, the context of your conclusion solution is what is setting you off. First look at sturm-liouville theory, then learn some real and...
20. ### Baby Rudin Theorem 1.11

You should definitely look at Real Mathematical Analysis by Charles Chapman Pugh. I find it much easier to read than Rudin. I honestly don't know why Baby Rudin is preferred by so many, I feel like Baby is sort of outdated and lacks organization of thoughts in some of his proofs. Your...
21. ### How to think of uniform continuity intuitively?

I really don't know if there is a good intuitive approach to uniform continuity. I'll try... The difference between the two is that with regular continuity, the ball of radius delta about some point c depends on how far you are away from c in the domain (delta depends on x and and epsilon). In...
22. ### Interchaning Limits and Inner Products

Exchanging limits and anything else, i.e. derivatives, sums, integrals depends on whether or not a sequence of functions is uniformly convergent. Since in Hilbert space, the inner product is either a sum for discrete or an integral for continuous cases, such a result is dependent on whether or...
23. ### How to derive beta function as pochhammer contour integral?

There are a vast number of beautiful results in complex analysis. This is indeed one of them. May I ask what plotting utility you used?
24. ### Calculating reciprocal base vectors

Thanks. I actually got through and understood everything in Simmonds without knowing that. It was just a problem I came across when going back and doing the exercises. I guess it wasn't explicitly stated, but it was supposed to be inferred at some point. I failed to realize that I actually had...
25. ### Parameterize a geodesic using one of the coordinates

I'm not sure if you can simply introduce a new equation when its not given. Have you tried to find an expression which yields the r equation after substitution? Such as an integrating factor so you could put it into sturm-liouville form? I don't have a pencil and paper right now but it just...
26. ### Calculating reciprocal base vectors

I have just started diving into tensor analysis. To be honest, I didn't know whether to post this question in the vector analysis forum or this one. I have looked at a few books on the subject and scoured the internet, but I can't seem to find anything that answers this question. Or, maybe I...