Local Definition and 521 Threads

Hello, just got done taking a test and one problem kinda confused me. Homework Statement f(x,y) = e^x cos y find local min/max and saddle points Homework Equations fx = e^x cos y fy = -e^x sin y The Attempt at a Solution I answered that there were no critical points for...

Does a constant function have a local maximum?

Homework Statement I am wondering how did the local graviational field (free fall acceleration) g = 9.81m/s^2 is calculated? Homework Equations The Attempt at a Solution

Let R be a ring . Suppose that e and f=1-e are two idempotent elements of R and we have R=eRe \oplus fRf (direct sum ) and R doesn't have any non-trivial nilpotent element . Set R_1=eRe and R_2=fRf . If R_1=\{0,e\} and R_2 is a local ring , then prove that R_2 is a division ring . (note that e...

Can anyone tell me about how to use the local density approximation in density functional theory analytically if it possible?

Suppose one had a solid sphere just slightly larger than its Schwarzschild radius. What would the curvature of the surface look like to a local observer? Would it curve downwards, or appear flat, or curve upwards? If my brain was working a bit better today, I'd calculate it myself from the...

Hey, To promote understanding of science I want to write a short article every week for my local newspaper. Four articles will be sent to them as a taster to get their agreement; a snippet, a column and two full length articles. Four subjects that are easily accessible and also...

Take the following setup: A series of pulses of radio signal is relayed around the world, along the equator. There is no "gap", it is a continuous loop along numerous relay stations build along the equator. The total number of pulses is fixed at 648,000 - I'll explain in a minute why that...

The effect of "local torques" on a free body(A hexapod robot) Hi I have a question regarding how torques affect a free body. I am making a dynamic model of a mobile robot with 6 legs. I'm treating the body of the mobile robot as a free body, with 6 forces acting upon it from the legs, plus...

1. Use the following equations to fill in the missing numbers. The correct addition and subtraction signs have already been entered. PROBLEM ONE: f(x) = ax4 + bx3 - cx2 - dx - e Find values of a,b,c,d, and e so that the function has inflection points at ((v3)/3, -7.5752) and (-(v3)/3...

Homework Statement h is the timestep Y' = F(Y) Mk,1 = F(Yk) Mk,2 = F(Yk + 0.5*Mk,1) Mk,3 = F(Yk + h*Mk,2) Mk,4 = F(Yk + h*Mk,3) Yk+1 = Yk + (h/6)*(Mk,1 + 4Mk,2 + Mk,4) Show that the local error is of fourth order The Attempt at a Solution I have written down the...

So much hay is made out of the fact that quantum theory—and its associated experiments—violates the principle of local causality, as canonically developed by the classical (Newtonian) and relativistic (Einsteinian) models. But no one ever really asks about what these models are 'truly' saying...

The question asks for local minimum of x^4-9x^3+9x^2+5x-4. The answer was x=-0.21 and 5.96. I thought 5.96 is the absolute minimum, since it gives the loweset y value on the open interval. Where am I wrong. Thanks.

Homework Statement Hey, so i need some help trying to find the local max and min points for y = sinxcox3x Homework Equations The Attempt at a Solution I know i need to find the first and 2nd derivative but i do not know if i am doing it right. I also do not know what to do after wards. my...

[b]1. An astronomer at the Dominion Astrophysical Observatory (DAO), located at latitude 48° 31' N in Saanich, near Victoria, B.C., is studying the K2 III star N'3148°α Arietis. The equatorial coordinates of α Arietis are right ascension=2h 07 m 30s and declination of 23°29' If the...

Hey my cousin wanted to be a civil engineer instead of an electrical. He got his electrical engineer at Carleton University http://www.carleton.ca/ . Anyway, when he asked them if any of his credits would transfer to civil engineer, they said "no" because and that he would have to do a civil...

For any constant c, define the function f-subscript c withe formula f-subscript c(x)= x^3 + 2x^2 + cx a)graph y= f-subscript c(x) for these values of the parameter c: c = -1,0,1,2,3,4. What are the similarity and differences among the graphs, and how do the graphs change as the parameter...

There have been many QM Interpretation thread, but I haven't found this question answered: Taking aside the fact that a complex probability amplitude is not something we can picture, is the Schrödinger equation local and deterministic at once?

Show that the function f(x) = x^21 + x^11 + 13x does not have a local maximum or minimum. So f '(x) = 21x^20 + 11x^10 + 13. My reasoning is as follows: Since the exponents (10 and 20) are even, 21x^20 and 11x^10 can never be negative, and thus, summing them can never produce a negative...

Number of photons operator can be define as follows: \sum a_k^\dagger a_k . Is it possible to define this operator locally and obtain operator \hat{n}(x,y,z)of local density of number of photons so that \langle \psi |\hat{n}(x,y,z)|\psi\rangle = \rho(x,y,z). Thanks for reply.

Hello I have a local stress acting radial on a thin cylindrical plate (see illustration), how can I calculate if the plate will deform/bend? I can only find equations for uniform external pressure (Marcel Dekker), but will it be okay when the stress is only local?

This is kind of an offshoot from: https://www.physicsforums.com/showthread.php?t=369328 Assume for a second that the controversial experiments are valid and Bell's theorem is true of the universe. I have often seen the philosophical analysis that if Bell's Theorem is true then either local...

Is it correct that theories such as the free complex scalar field or the free Dircac field with their global U(1) symmetry give rise to only globally conserved charges (a globally conserved Noether charge)? If so, how can that be shown? Also, is it somewhat correct to say that the main reason...

Homework Statement I am using the boundary element method to solve unknowns to the Laplace equation from classic potential flow theory for the time evolution of a fluid air interface. At each time step, I need to solve a material derivative equation numerically at every node along an interface...

how can i find the x-coordinates of all local extrema in this equations please anyone could answer it for me? f(x)=x^3+4x^2+2x f(x)=x^4-3x^2+2x f(x)=x^5-2x^2-4x f(x)=x^5+4x^2-4x

how can i find the local extrema of x-coordinates in this equation? f(x)=x^4-3x^2+2x

Non-spatial resolution of quanta (split off from "Local realism ruled out?") I have taken the liberty of creating a new thread since this sub-discussion in https://www.physicsforums.com/showthread.php?p=2561841&posted=1" had diverged a bit from the OP. You distinguish two isomorphic...

K, so I don't quite understand how I find a persons weight on a different planet using the said person's weight, the mass of the other planet, and the radius of the planet? So, for example: Max weighs 1000 N on Earth. What would his weight be on a planet with twice the mass of Earth, but...

Thank you for the suggestion. I should say this is the first thread I am starting since I joined physics forums four years ago. So this thread has branched from another one -"Photon entanglement and fair sampling assumption". I noted there that, on the one hand, so far no experiments...

In another thread, we were discussing Zonde's and the De Raedt's model for simulating Bell tests using a purported local realistic computer simulation. I have broken out into this new thread some results which will be interesting to those of you interested in this subject. I will start out by...

It is my understanding that in string theory, loop quantum gravity, the 'asymptotic safety' approach, and in semiclassical quantum gravity, local Poincare symmetry is exact. But there are things like DSR (does the D stand for Deformed, or Doubly? I've heard people say it either way), which...

Homework Statement Given a BVP: \Delta(u)+u=1 in \Omega u=0 on \partial\Omega using linear piecewise functions, calculate the corresponding local stiffness matrix on the reference triangle : {(x,y); 0<=x<=1, 0<=y<=1-x}. The domain is a square with one point in the middle (at...

I just have a small question regarding lorentz cavity: Refer to a small lorentz cavity in a uniformly polarised dielectric. as shown in fig. E_{ex}: External electric field. E_{P}: Electric field in the uniformly polarised dielectric (when sphere has NOT been cut out) E_{L}:Electric field...

Hi, I understand that the local max of a function is the point at which the y value of the function is larger than the neighbouring y values of the function. Say we're considering the local max at a of a function f(x). Does the function have to exist on both sides of a for (a,f(a)) to be a...

Homework Statement Find intervals on which function is (a) increasing (b) decreasing (c) concave up (d) concave down (e) local extreme values (f) inflextion points of: Y=1+x-x2-x4 Homework Equations Y=1+x-x2-x4 The Attempt at a Solution (a) To find where function is increasing...

Is there a space that is path connected but NOT locally path connected? I suspect that there must be some example because the theorem on the classification of covering spaces only applies to spaces that are, amongst other things, path connected and locally path connected.

I'm puzzling over a certain aspect of the interpretation of frame-dragging. Frame-dragging says that the angular momentum of a body makes itself felt in a certain way in the curvature of the spacetime surrounding it. In GR, you typically can't point to a certain spacelike surface with a...

I've just listened to an online lecture where Susskind explained Bell's inequality () Basically he shows that classically A\cap \overline{B}+B\cap \overline{C}\geq A\cap\overline{C} Then he uses spin measurements with 0°, 45°, 90° to the z-axis for A, B, C to measure spins of an electron...

Hi all! This is a generic Mathematica question, which hopefully someone can help me with! :) I have a set of data points. I have an interpolating function from those points. I have a graph of that interpolation function. The graph goes like Sin^2, and has about 10 peaks. I want to have...

Homework Statement http://img682.imageshack.us/img682/1220/86316124.jpg Homework Equations The Attempt at a Solution why am i getting this wrong? i am pretty sure about everything and nothing else seems to fit in there.. maybe the last one? but it says decreasing so it must be...

f(x) = cosx, a = \pi/2 since, L(x)=f'(x)(x-a) -f(a) f'(x) = -sinx = -sin(\pi/2)(x-\pi/2) - f(a) I'm stuck as to where to go next, is this even right?

Homework Statement http://img4.imageshack.us/img4/8899/85779053.jpg Homework Equations The Attempt at a Solution could you please check my answers.. I am pretty sure they are good but i just want to be sure.

Well I've got a temporary full-time job at a local Wendys. Needed the money really badly as I quit my last job and was jobless for a while (my stupidity lol). Anyways back to the job. I've worked at a McDonalds before for 2 years so I was able to get this job relatively quickly... I never had...

Homework Statement Consider a function of one variable, f(x), which is continuous on an interval I. If f has a single critical point, x = a, in I, then if that point is a local maximum (or minimum) it must also be an absolute maximum. Explain why this is.Homework Equations Intermediate Value...

Hello Forum, Using a fixed, Cartesian reference frame (i.e., we, observers, are stationary and located at the origin of the system), the trajectory of a particle would be easily described by the parametric (parameter time or arch length) equations [x(t), y(t), z(t)] or [x(s),y(s),z(s)]...

Many interesting proofs in GR (regarding black holes and singularities, etc.) involve topological methods. However, I don't understand how a theory embodied in Einstein's equations, which appear to me to be local rules of evolution, can ever change the topology since a patch of spacetime...

What is a local invariant? For instance, at http://en.wikipedia.org/wiki/Differential_geometry#Symplectic_geometry it is said that curvature is a local invariant for Riemannian geometry. What is meant by that? What are other examples of local invariants? Thanks!

I would like some tips about what book I should read if I want to properly understand the relation between local symmetry and forces in gauge theories. And with properly uinderstand I mean a combination of mathematics and intuition/visualization. On the topic of QFT I have the books by Zee (...

http://arxiv.org/abs/0908.3408

Homework Statement Show that the function f(x) = \frac{x^8 + 9x^9 - 12x^{13}}{1 + x^3 - x^6} has a local minimum at x = 0. Homework Equations The Attempt at a Solution If f is to have a local minimum at x = 0 then we must have f'(0) = 0. Without typing up the tedious...