Variables Definition and 1000 Threads

Hey everybody I'm developing a computer program that can take a series of data-points and estimate the next local maximum(top) of a sine-curve. My approach to this is to take the formula for a sine-function(f(x)=Asin(\omega x - \phi) + B), and isolate all the variables, and that way I'll...

Hi all; I need some clarification in red part; in how it is deduced from the theorem 2.5.6! I know how the blue is deduced from the theorem but don't even know how to get blue form red in practice!(No algorithm is suggested...) Anyway, any explanation is thanked... Regards.

So I have a list of variables, defined in my workspace, and I'm trying to access them each in turn to compare them to a larger matrix A. The eval function calls each variable in turn, stores it under temporary matrix B, then compares it to matrix A, does the necessary calculation, and stores it...

Hi all, I would like to find the distribution (CDF or PDF) of a random variable Y, which is written as Y=X_1*X_2*...X_N/(X_1+X_2+...X_N)^N. X_1, X_2,...X_N are N i.i.d. random variables and we know they have the same PDF f_X(x). I know this can be solved by change of variables technique and...

Hello, I am trying to understand how to solve a system of two variables (let's say s and p representing two physical quantities), where there is a third-order polynomial representing each. I'm not sure I am describing this correctly in words, but here is the system I need to solve. P = a0 +...

As an electrical engineering student can learning about complex variables be beneficial to me? If so can someone recommend an introductory book that I can read on my own? Also I have very little experience working with complex variables.

hello! I'm trying to understand the following property: Let X and Y be independent random variables z: = X + Y. Then http://imageshack.us/a/img268/9228/71pe.png where fZ (z) is the probability mass function for a discrete random variable defined as follows...

... ... I am curious to know why we have to multiply with e^{-j\omega t} in Fourier transform? What is the purpose of this? I have heard somewhere that the transform is merely a change of variables from one set of coordinates to another. I would like to know more about this. Can you help me?

So I've never really understood this idea of a light-cone. I know there is literature, but what are the most important physical concepts/consequences about this light-cone model of special relativity? Also, could you give a concise explanation of light-cone variables?

Realised I probably posted this in the wrong forum before, should've been here.. I often see a function's differential expressed in terms of convenient partial derivatives eg dU=(dU/dT) dT + (dU/dV) dV And I've seen it written that "any system is uniquely specified by two parameters, such...

Homework Statement When possible express the general solution in explicit form. Solve dy/dx =x^2 /(1+y^2) Homework Equations This is a first order non-linear ordinary differential equation. The Attempt at a Solution dy(1+y^2) = x^2 dx Integration both sides returns: y+ (y^3 )/3=...

Solve each differential equation. Express the general solution in explicit form. y' = (3x^2 -1) / (3+2y) So, I will skip many steps, because they are easy. However, I am stuck in one of the last ones. y^2 +3y = x^3- x +C y(y+3)= x^3 - x +C I have seen the solution for y...

Homework Statement [2 Dimensional infinite square well] Show that you can separate variables such that the solution to the time independent schrodinger equation, ## \hat{H} \psi (x,y) = E \psi (x,y) ## can be written as a product state ## \psi (x,y) = \phi (x) \chi (y) ## where ## \phi (x)##...

Hi! I was wondering: is it possible to have a non-orientable surface in 3D which is parametrized by u and v, with u and v periodic (i.e. is it possible to map the torus continuously into a non-orientable surface in 3D?) If so, does anyone have any explicit examples?

Homework Statement Determine if f(x,y) = ((x-y)4 +x3 +xy2)/(x2+y2) [f(x,y = 0 @ (0,0)] is differentiable at the origin. Homework Equations x = (0,0) The Attempt at a Solution A function is differentiable at x if f(x+Δx) - f(x) = AΔx + |Δx|R(x) Where A are constant...

Hi, Homework Statement The sample space of the following problem is defined thus: all the possible permutations of {1,2,3} including {1,1,1}, {2,2,2}, {3,3,3}. Suppose all results are equally probable. Let Xi denote the value of the ith coordinate, where i=1,2,3. I am asked to determine...

The following is identically 0 which can be readily checked by a simple hand calculation. $\binom{n+1}{k}2^{-n-1} - \binom{n}{k}2^{-n} + \binom{n}{k}*2^{-n-1} - \binom{n}{k-1}2^{-n-1}$ If you enter this in SAGE or Mathematica, using the appropriate script, and use full_simplify() and...

Homework Statement Evaluate the integral: ∫ x^{m}* (ln(x))^{2} It's said as ln squared x. Sorry if I miswrote it.Homework Equations ∫udv= uv - ∫vduThe Attempt at a Solution u= (ln(x)^2) v= x^{m+1}/(m+1) du= 2lnx/(x) dv= x^{m} * dx - ∫2lnx * (x^{m+1})/(x*(m+1)) + [(ln(x)^{2}) (x^{m+1})/(m+1)}...

If we think of a functional as a function of the infinite number of taylor coefficients of the variable function, aren't they then just normal functions, a map between a set of reals to another set of reals.

ℂI am working on an assignment and have come across a question that I'm not quite sure how to approach. Here it is, with my "solution" and reasoning: "[F]ind the limit at ∞ of the given function, or explain why it does not exist. 24. h(z) = Arg z , z \neq 0" (Complex Variables Second...

the random variables X1,X2... are independent and they take 0 and 1 values and they have expected value 0 if we have Y=X1+X2+...+Xn and Z=X1+X2+...+Xn+Xn+1 what is the ρ(Y,Z) for n=46 i know that ρ(Y,Z)=cov(Y,Z)/(sqrt(var(Y)*sqrt(var(Z)) but i need some help on how to find the cov and vars...

Hi, Let's say I'm given X and Y identical independant continuous random variables. We pose Z =X/Y, I remember there is a way to find the density function of Z, altough I can't get to remember how to do it and my probability book is out of town.(And I'm not so sure what to look for in google)...

Dear All, If I have the linear algebraic system where its composed as of matrices in that form K*X=F, what column/row operations should I perform if I want to solve it where some of the X variables are known (targeted values) or if I want to solve when variables are constrained relative to...

we have X,Y variables and we have f(m,n)=P(X=m,Y=n)=C*((1/(a*m*n+15*m+11*n+8))^2) for what value of a X,Y are indepedent? ( its not necessary to calculate C) i know that f(m,n)=f(m)*f(n) if X,Y are independent but how i am going to use this for calculate a?

Hi I have a certain experiment that I repeat 40 times and get the result: 0.001 +/- 0.004. Now I've repeated the experiment using a different method (so it is essentially a new experiment) and I get a new value: -0.002 +/- 0.003 Now, is it true to say there is no statistically...

Greetings- In trying to solve a thermal stress problem, I have encountered an inhomogeneous differential equation of the following general form: \nabla^2 \Phi(r,z) = F_r(r)F_z(z) Solving the homogeneous case is no problem, as it is kind of a classic. Is there a route to finding a particular...

Dyadic Cube C_{k,N} = X \in\ \mathbb{R}^{n} \frac{k_{i}}{2^{N}} \leq x_{i} < \frac{k_{i}+1}{2^{N}} for 1 \leq i \leq n Where k = \pmatrix { k_{1} \cr k_{2} \cr \vdots \cr k_{i} \cr } I understand that N is the level of the cubes, but what does k equal? I'm having trouble...

Homework Statement Let S be the part of the cylinder of radius 9 centered about z-axis and bounded by y >= 0; z = -17; z = 17. Evaluate \iint xy^2z^2 Homework Equations The Attempt at a Solution So I use the equation x^2 + y^2 \leq 9, meaning that r goes from 0 to 3 Since y...

Evaluate the limit or prove that it does not exist.. f(x,y) -> (0,0) 3xy/((x^2)+(4y^2)) The attempt at a solution: Set x to 0 and you get 0 set y to 0 and you get 0 set y=x and you get 3x^2/5x^2 = 3/5 This means that limit does not exist. Is this correct? If this is correct, how...

we have X,Y variables and their common density f(m,n)=P(X=m,Y=n) where f(0,1)=0.1 f(1,0)=0.1 and f(1,1)=0,31 find P(X=0) i think that P(X=0)= f(0,1) but it says that its incorrect what i am doing wrong?

Homework Statement I can't see where the problem is in the following pseudo-code. I recall from class that the problem is based on the signal calls and wait call in pickup() and putdown() Thank you. Homework Equations class Monitor R() { bool forks[5]; // all true condition c[5]; void...

I have a question regarding the paper by John Bell (www.drchinese.com/David/Bell_Compact.pdf‎ ) in which he shows that a certain hidden variable approach cannot reproduce the expectation values predicted by QM for a pair of particles in the singlet state. After eqn 15 on page 4, I don't...

Hello. I have a problem with probability theory task. The task is: X and Y is independent random variables with same density function fx=fy=f. What will be probability of P(X>Y). This P(X>Y) reminds me a cdf: P(X>Y)=1-P(X<Y)=1-cdf of X. Cdf of x is equal to integral ∫f dx from -inf to...

Let x(1),...,x(N) all be independent uniformally distributed variables defined on (0,1), i.e. (x(1),...,x(N)) - U(0,1). Define the random variable y(i) = x(i)/(x(1)+...+x(N)) for all i=1,...,N. I’m looking for the pdf of the random variables y(1),…,y(N). Has anyone come across such random...

Give a parametric equation for a curve in 2 dmiensions (x(t),y(t)) it may sometimes be possible to rotate or otherwise transform coordinates so that the tranformed curve becomes a function y = f(x) (as opposed to merely a relation such as x^2 = y^2 + 1). More generally, if we have a curve...

Homework Statement I have to design an experiment with 3 factors. One factor has to be quantitative with at least 3 levels. One Qualitative with at least 3 levels. And the last one can be either quant/qual with at least 2 levels. My question is in regards to coding the variables. For example...

http://sphotos-h.ak.fbcdn.net/hphotos-ak-ash4/485580_10200547582988715_854455727_n.jpg In formula 1 it says F(1) = F(0)+F'(0)+ 0.5F''(C) Where the heck dos the C come from? I thought they were applying taylor's formula to find an approximation of F(1), around t=0. Then c=0, right? Is it...

From the two equations given below, find ∂s/∂V (holding h constant) and ∂h/∂V (holding r constant V = π*r^2*h, S = 2π*r*h + 2*π*r^2 Not entirely sure where to start...

Homework Statement We have two independent, exponentially distributed random variables X and Y (with parameter a). Z = X/(X+Y) What is Z:s distributon function? Homework Equations The Attempt at a Solution I think I need some intuition to what I'm really doing with these, I'm having a...

1. Homework Statement [/b] this problem is on page 267 of Advanced calculus of several variables by Edwards, I just can't seem to get a handle on it: Let aA be a contented set in the right half of the xz plane ,x>0. Define $$\hat{x}$$, the x-coordinates of the centroid of A, by...

Homework Statement $$u_{tt} = a^2u_{xx} , 0<x< l , t>0 , $$a is constant $$ u(x,0)=sinx , u_{t} (x,0) = cosx , 0<x< l , t>0 $$ $$ u(0,t)=2t , u(l,t)=t^2 , t>0 $$ Homework Equations The Attempt at a Solution I can solve the eigenvalue problem of X(x), and then solve for T(t), but...

Homework Statement Find correlation between random variables x and y in the following: $$P_{x,y}(x,y)=A \ xy \ e^{-(x^2)}e^{-\frac{y^2}{2}}u(x)u(y)$$ Homework Equations The co-variance ##\sigma_{xy}=\overline{(x-\bar{x})(y-\bar{y})}## or ##\sigma_{xy}=\overline{xy}-\bar{x}\bar{y}##...

I didn't post this in the probability section cause the questions I have are more regarded to communication system engineering. I haven't actually been able to wrap my head around these concepts mainly cause all the study material I use have these really ambiguous explanations of each...

Hi, I would certainly appreciate it if you could please confirm the result I obtained to the following Statistics problem. Homework Statement A tank is supplied with fuel once a week. If the fuel (in thousands of liters) that the station sells in a week is a random variable which is...

Homework Statement The question is: Let \phi: \mathbb{R}^n\rightarrow\mathbb{R}^n be a C^1 map and let y=\phi(x) be the change of variables. Show that dy_1\wedge...\wedge dy_n=(detD\phi(x))\cdotdx_1\wedge...\wedgedx_n. Homework Equations n/a The Attempt at a Solution Take a look at here and...

The question is: Let $\phi：\mathbb{R}^n\rightarrow\mathbb{R}^n$ be a $C^1$ map and let $y=\phi(x)$ be the change of variables. Show that d$y_1\wedge...\wedge $d$y_n$=(detD$\phi(x)$)$\cdot$d$x_1\wedge...\wedge$d$x_n$.Take a look at here and the answer given by Michael Albanese: differential...

Hi everyone, I have the following exercise. Fx(x)=0, x<-1 or x>1 Fx(x)=1/2, x=[-1;1] g(x)=x^2+1 --- this is the function of random variable I must calculate Fy which is the sum of solutions of g(xk)=y , Fy(y)=sumFx(xk)/|g`(xk)| g(x) is bijective on [-1;1] y=x^2+1=> x=+sqrt(y-1) or x=-sqrt(y-1)...

Hi, I'm trying to find a probability distribution (D) with the following property: Given two independent stochastic variables X1 and X2 from the distribution D, I want the difference Y=X1-X2 to have a uniform distribution (one the interval [0,1], say). I don't seem to be able to solve it...

For some time now I've been trying to figure out probably for a problem of the following form. Say a criminal profiler is trying to determine the probability that someone is a criminal based on statistical information. 60% of people who have mustaches are criminals. 70% of people who...

Hi Everyone! I have two normally distributed random variables. One on the x axis, the other on the y axis, like a complex normal random variable. I'm trying to find the pdf of the angle between a fixed point on the x-y plane(let's say point 1,0) and the vector formed by combining the two...