Mean Definition and 1000 Threads

The function for simple harmonic oscillation is: Acos(ωT)+\phi Why is there an angle phi added to the function acos(ωT)?

hello , I don't understand the meaning of the next definition , so , I hope that you can make it easy to understand it for me definition if G is an arbitrary group and ∅≠S⊆G , then ,the symbol (s) will represent the set (S) = ∩ { H∖S ⊆ H : H is a subgroup of G } can you give me some...

Hi all, I got an idea why noise is having a gaussian pdf but didnot understood why it should be having zero mean. Why can't noise contain a dc content. -Devanand T

Homework Statement Let D be a division ring, C its center and let S be a division subring of D which is stabilized by every map x -> dxd-1, d≠0 in D. Show that either S = D or S is a subset of C. 2. The attempt at a solution I haven't actually started working on it yet because I am not...

Hi there, I am going thru basics of optimization and I see line search being used in many sophisticated optimization algorithms. From what I understand, it works by taking the derivative at a point and moves in a direction that minimizes the function. I have earlier experience using...

The universe is expanding, I am told by a friend who is well-trained in such matters, not only in its spatial dimensions, but also in its time dimension. This sort of suggests that there is now more time between the beginning of time and yesterday than there was when it was actually yesterday...

Homework Statement This is Purcell 4.12... Given that conductivity in silicon at 500K is 0.3 sec-1, deduce the mean free time between collisions of an electron. Homework Equations Electron mass is 9.1x10-28 grams (mass of a hole is exactly the same), the charge on an electron is...

Hi guys, I have to find the deviation from the mean for each individual entry of a column of numbers. Any one have any idea how to do this? I'm clueless when it comes to excel

I was assigned a multistep task by my professor so I first made the molecule with ChemDraw, then I ran an optimisation using B3LYP/6-31G. I then ran a frequency scan and checked for any imaginary frequencies. There were no negative frequencies and my understanding is that this means that...

Homework Statement So the question is, given a set of random numbers, find the mean and the value that will be >= 99% of the occurances. So for a set of random numbers between say, 1-100, if the mean is 50, how do I find out what number will be >= 99% of all observations of the time...

Hi, I'm a masters student trying to apply DMFT to problems involving transport in strongly correlated systems. I have a cursory understanding of the physics behind the Hubbard model, which is to say, I have spent some time with it in a quantum many body theory course. However, I now want to...

Homework Statement Prove that the only surfaces with zero mean curvature are either planes or hyperbolic curves with the equation: y = \frac{\cosh (ax+b)}{a} rotating alone the x axis.Homework Equations The Attempt at a Solution I made an attempt by devoting the equation of the surface as r =...

In relational algebra what does "in" mean? For example \sigma_{car IN car}R where R is some relation.

What exactly do the terms "near-field" and "far-field" mean? What exactly do the terms "near-field" and "far-field" mean (especially in the context of the two problems attached)? Other than the confusion about those terminologies, I fully get how to do these problems (1.1 and 1.2). Any...

Hi Guys, I am just starting readings on machine learning and came across ways that the error can be used to learn the target function. The way I understand it, Error: e = f(\vec{x}) - y* Loss: L(\vec{x}) = \frac{( f(\vec{x}) - y* )^2}{2} Empirical Risk: R(f) = \sum_{i=o}^{m} \frac{(...

I'm reading a finance book in which the author proposes to exclude the mean when calculating the variance of returns, because he thinks it's difficult to distinguish the drift of the price from the variance of that time series. So he basically calculates the sample variance like this...

I hope this the right place to ask this question. I appologize if this is in the wrong place. I am not from a probability background. I have tried to search for an answer to my question, but I have not found it in any of the literature which I can understand. I'm not even sure exactly how to...

Homework Statement A recent summary for the distribution of cigarette taxes (in cents) among the 50 states and Washington, D.C. in the United States reported mean = 73 and standard deviation = 48. Based on these values, do you think that this distribution us bell-shaped? Justify your answer...

What does "rest" mean? If I throw a ball straight up, at its highest point, is it momentarily at rest? Its velocity is momentarily 0, but it is still accelerating.

I would like to know what this symbol means:\nVdashSpecifically, in the main result of [link] (Theorem 1, at the top of p.4), it has:\nVdash(n=k=0)

Strictly not so much an academic guidance question, but I don't know where else I can put this. In the U.S., What's the typical letter grade you get if you're around mean in a course in college? From where I'm from, being mean in class equates to a B- or a C+, and I'm just curious to know...

Homework Statement Assume that X is squared-Chi-distributed, which means that the moment generating function is given by: m(t)=(1-2t)^{-k/2} Use the mgf to find E(X) and var(X) The Attempt at a Solution I know that m'(0)=E(X), and m''(0)=var(X). So I find...

Hello Everyone, I have a 5 ampere weighing equipment & need it to ground properly. It is about 80 feet away from soil point. (Direct wire to the equipment will be used & long term connection is required). Manufacturer says that: "There must be a good third wire ground, preferably to a...

What do you mean by "countably infinite"? I just couldn't understand the meaning of countably infinite. I have seen some definitions but I couldn't get an insight. Could you please help me in understanding this term with some kind of an example? Thanks a lot. :)

I am supposed to use the mean-value theorem to show that lim_x→infty(√(x+5)-√(x))=0. Can anyone help me solving this problem? I have tried to set up the mean value theorem, but i just do not know how to proceed.

Hi, I have a question regarding quantum teleportation. I understand that Alice starts of with a photon A whose state she wants to teleport. Alice and Bob share an entangled pair of photons, B and C. Then Alice does something called a Bell measurement which entangles A and B and the result...

My QM book introduces operators like the momentum operator \hat{\mathbf{p}} which act on their eigenstates to produce new states like \hat{\mathbf{p}}|\mathbf{p}\rangle = \mathbf{p}|\mathbf{p}\rangle. But how can we interpret a state like that? How is multiplication between a Euclidean vector...

what do we mean by spin of a particle when we say it a point particle?how do we measure spin experimentally and give it values like +1,+2 etc. what does it mean by a spin 0 particle?

What does it mean to be "strictly-strictly" continuous? I am unsure what it means to be "strictly-strictly" continuous. Is that the same thing as saying just "strictly" continuous? Here is the context: \alpha is a unital *-homomorphism from M(A) to \mathcal{L}(A) such that \alpha is...

Wondering if it is possible to reconstruct a dataset if I give you the mean, median, standard deviation and N of a dataset. For example, if there are 20 students in a class. The mean of their exam score is 80, median is 85, standard deviation is 14. Of course the maximum score for the exam...

Suppose a person takes data (say counts per minute of cars going past his window), for a long time. Then he loses his data, but knows that he counted 5 cars more often than any other number. What is the likely range for the average count rate? I tried to solve this by saying the mode is 5, so...

Hello, Just had a question regarding statistical analysis. I'm trying to calculate the average of 4 numbers from a data set of 6 numbers in excel without manually choosing to average only the 4 numbers. e.g. 85 20 32 45 27 3 (total mean = 35.3 desired mean = 31) 100 30 27 40 21 1...

Let Pr(X_{i} = +1) =\frac{2}{3} = 1 - Pr(X_{i} = -1) , and S_{n} = \sum{X_{i}}, For each k≥1, define T_{k}\ =\ min \left\{n≥1: S_{n} = k \right\}. Calculate E[T_k], and Var[T_k]. 2. Homework Equations E[T_k] = \sum_{n=1}^{n=∞}{n Pr(T_k = n)} , and E[T_k]^2 = \sum_{n=1}^{n=∞}{n^2 Pr(T_k...

Hi, I am wondering how i can calculate the classical mean free path of electrons in InSb given the following material parameters... zero field conductivity = 1.86e4 1/ohm m electron mobility = 45,500 cm^2/Vs Is it a case of working out the scattering time and multiplying it by the...

Given f(n) = (1 - (1/n))n I calculate that the limit as n -> infinity is 1/e. Also given that x/(1-x) > -log(1-x) > x with 0<x<1 (I proved this in an earlier part of the question) I want to show that: 1 > (f(60)/f(infinity)) > e-1/59 > 58/59 I have tried using my value for f...

Other than the fan and hardrive, nothing else seems to be moving...

What exactly do we mean by nothingness?Im asking about when this universe was not present..not about space.

I learned the formulas F = G \frac{m_1 m_2}{r^2} and F = m \cdot a and also saw mathematically that objects have the same gravitational acceleration and will fall down at the same rate, also demonstrated in a video by people that were on our moon, even though one object clearly has more force...

If I you like Beethovens music does that mean that you "just dont just don't have the mental capacity to appreciate it yet" EDIT: ok the title was supposed to say "If I you DONT like Beethovens music does that mean that you "just don't have the mental capacity to appreciate it yet" ...

Homework Statement I am reading the Griffths book on quantum mechanics. In the first chapter on Momentum (Sect 1.5) what does d<x>/dt mean in the physical sense? Homework Equations NA The Attempt at a Solution If the expectation value <x> is already determined by the schrodinger...

Hi Guys, I am trying to measure variability in a part for my sensor which l do not know the true value. So l decided that a good way to measure variability in this case would be to measure precision of my data points as l change this part on the sensor. So l was wondering, can l compare the...

Hello, I have come across the following equation and want to know what the notation means exactly: \frac{-2 \pi \gamma}{\sigma} \frac{[ber_2(\gamma)ber'(\gamma) + bei_2(\gamma)bei'(\gamma)]}{[ber^2(\gamma) + bei_2(\gamma)]} Now, I know ber is related to bessel functions. For example, I...

I see this often and am not sure what it means. Suppose X and M are any two elements: X1-xMx Thanks.

Hi All, Is it possible to express the kurtosis \kappa, or the 4th central moment \mu_4, of a random variable X in terms of its mean \mu = E(X) and variance \sigma^2 = Var(X) only, without having to particularize to any distribution? I mean, an expression like \kappa = f(\mu, \sigma^2) or \mu_4...

I see this at a Wikipedia article: http://en.wikipedia.org/wiki/Cyanoacrylate

Homework Statement Let f(x)=log(x)+sin(x) on the positive real line. Use the mean value theorem to assure that for all M>0, there exists positive numbers a and b such that f(b)-f(a)/b-a=MHomework Equations f'(x)=1/x+cos(x) The Attempt at a Solution I know that as x→0, f'(x) gets arbitrarily...

Homework Statement Could anybody please explain this notation? The only thing I undersand here is the limit. Is r a superscript? If not, what is it? And what does E(variable|condition/equation) mean? I know that in the set theory, | means a separator between the variable and condition (ex...

Homework Statement This is no homework question, i could not understand a statement from the book Complex Numbers from A to ...Z because i don't know the meaning of the symbol used. Here is a screenshot: The problem is what does "n|q" mean? Any help is appreciated! :smile:

Hey there, not sure if I am posting this in the right place, so I apologize if I am not. So after some calculation I came up with an average human cell yielding 8.9876e+3 joules if annihilated. But what does that figure mean in the real world? I suppose I am looking for an analogy here...

I am going into third year (junior) in the coming fall and I plan to do some research over the summers with a prof I know. I've talked with the prof and he seems to be willing to take me on. However I have one concern is if I can graduate within four years. To make that happen, I have to...