Parameters Definition and 489 Threads

Homework Statement Could anyone please help me understand this notation? What is "it" under the variables? Is it some kind of sequence notation with 2 dimensions, or sequence notation which has the sequence member number multiplied by some other variable? What is this? Also, what could 0...

Hi guys, I'm dealing with a function whose integral (via Wolfram integrator) carries a hypergeometric function term: 2F1(\frac{1}{4}, \frac{1}{2}, \frac{3}{2}, z). I need to evaluate this function twice for every integral, but |z| will often be greater than 1, so I can't use the hypergeometric...

Homework Statement y''-2y'+y = \frac{e^x}{1+x^2} Homework Equations u_1 = -\int \frac{y_{2}g(x)}{W}dx u_2 = \int \frac{y_{1}g(x)}{W}dx g(x) = \frac{e^x}{1+x^2} W is the wronskian of y1 and y2. The Attempt at a Solution The characteristic equation for the homogenous solution...

Hello... The concept that resistance can be for a dc supply only and not for the ac supply coupled or superimposed to the same circuit, is something i don't understand to this moment... I first realized this in diode systems... where i saw bulk resistance for DC and dynamic resistance for AC...

Hello everyone :) The CMB is polarized. I read in Dodelson's book "Modern Cosmology" that we can expect a signal of polarization weaker than the signal of temperature. Is it only because the Stokes parameters obey $$I^2 = Q^2 + U^2 $$ (I drop V because Thomson scatering can't create V...

Homework Statement Eliminate the parameter: x=2-3θ y= 4+θ Homework Equations x2 + y2 = r2 The Attempt at a Solution [x=2-3θ]2; [y= 4+θ]2 x2= 4-12θ+9θ2 y2= 16+8θ+θ2 ------------------------------------- x2+y2 = 20 - 4θ + 10θ2 r2 = 20 - 4θ + 10θ2 Is there another...

Hello Forum, This is my first time on this forum, so, please, forgive me if I've mistaken the right section for the following question. For my research, I need to know the values of LJ pair-potential parameters: the depth of the potential well and the distance at which the latter becomes...

In oscillation experiments that use solar neutrinos, it seems that the mixing angle \theta_{12} and the mass squared difference \Delta m_{12}^2 can be determined from comparing measurements of the neutrino flux to theoretical models of what the Sun should be emitting. However, I am...

Homework Statement y'' + y' = 4t Homework Equations Use Variation of parameters! The Attempt at a Solution So I get homo of: c1 + c2 e^-(t) From there I get a Wronskian of -e^(-t) Then I get variations 2t^2 and -4e^t(t-1) Then get the answer of 2t^2 + 4t - 4 Btu...

I'm having a lot of trouble with the subject. Here's one example I'd like explained. F(t_1, t_2) = \int \limits_0^1 x^{t_1}\ln^{t_2}\frac{1}{x} dx The book asks to find for what \vec{t} F converges. The answer is \vec{t}\in(-1; \infty)^2, but I don't see how to get that. In general, what...

Hey guys, Just need some help with this question, It asks for the answers to be in circuit parameters: http://tinypic.com/r/k0k2ed/5 For some reason I don't think my answers are correct as I'm finding it hard to make sense of my answers to the questions. a)Find the voltage Vab (magnitude and...

Hi all! I have a question about fortran. So far in my coding, if i wanted to define a function ( say f(x) ) I would manually set a grid for x, and then define f for each x value, so that i would have a vector for f and a vector for x. However, I'd now like to use the 'function' command, so i can...

I know the generalized formula for Feynman parameters, my problem is in simplifying. What I mean is something like this: Take the simplest 3 parameter equation \frac{1}{ABC} = 2 \int_0^1 dx \int_0^1 dy \int_0^1 dz \frac{ \delta \left( 1-x-y-z \right)}{(xA+yB+zC)^3} And you can take this...

Hello Guys! I have an ODE problem that I'm solving it by MATLAB ODE solvers! in fact I have a system of non-linear differential equations in one of these equations I have a parameter that it's value is dependent to derivative! the general form of equation is like this (big letter parameters...

I'm having trouble with understanding how methods that have a parameter work. For example, public class Register { private double purchase; private double payment; public static final double QUARTER_VALUE = 0.25; public static final double DIME_VALUE = 0.1; public static final...

Hi, I understand that a 3x3 unitary matrix needs 9 real parameters to be specified (18 real parameters to start with then 9 equations of constraint arising from unitarity), but what I'm struggling to understand is how we can make phase changes of the form: \mathrm{e}^{-i\beta_I} V_{IJ}...

I am trying to solve the general equation for a body falling in drag so I can apply it to many objects. But Mathematica seems to have problems with having anything but numbers and your independent and dependent variables as an argument. So if I want to leave the mass, a constant with respect to...

Homework Statement Solve y''+25y=10sec(5t) Homework Equations NA The Attempt at a Solution I believe I have the correct answer for yp which is: 2/5log(cos(5t))cos(5t)+2tsin(5t) When I plug this into the Webwork field, it says it is incorrect. I checked my answer against...

Hey ya'll! This is the equation under discussion: y'' - 2y' - 3y = x + 2 I'm asked to use the method of variation of parameters to determine a solution for this differential equation, but I reach a point where my the equations just look too ridiculous to continue. The point I have in...

Homework Statement what is general solution of 2y'' - 3y' + y = ((t^2) + 1)e^tHomework Equations my particular solution is: (e^t) ((2/3)(t^3) + 6t -4)) prof particular solution is: ((1/3)(t^3)(e^t)) - 2(t^3)(e^t) + 9(te^t) The Attempt at a Solution here is how i solved , i hope this is ok to...

Show that $\displaystyle \int_{0}^{\infty}\frac{x^{\alpha-1}}{(w+x^{\beta})^{\gamma}}\ dx = \frac{w^{\frac{\alpha}{\beta}-\gamma}}{\beta} B \left( \frac{\alpha}{\beta}, \gamma - \frac{\alpha}{\beta} \right) = \frac{w^{\frac{\alpha}{\beta}-\gamma}}{\beta} \frac{\Gamma \left(...

Hi there, just wondered if someone could help me? I have a set of data from an experiment and have fitted a cosine fit to it. If the theoretical model for dark matter I have says the value for θ should be,say 2, and the cosine I have fitted has a θ=2+2.2σ, how could I go about saying for...

Homework Statement A projectile is launched with a speed v at an angle theta above the horizontal. Ignore air resistance. Derive an expression for the angle theta in terms of the parameters of the problem such that the horizontal distance from the launch of the object is N times greater than...

Can anyone explain to me how are the parameter passed on to the function in C++?

Homework Statement Find the h parameters of the following systems:- ---L---------C-- : : R : : ---------------- L= j5 ohm C=-j5 ohm R=1 ohm Homework Equations The above questions has to be solved manually as well as simulated...

Hello every body... Consider two port system having a resistor (can it be called two port system?)... ____---->I1________________I2_<----_________...

Homework Statement Measurements of the height h(t) of water in a harbor are recorded ,where h is measured in meters and t in hours.It was noted that the rise and fall of a tide is modeled by a sinusoidal function giving the height by : h(t)=a+bsin(kt+c). (a) Obtain values of the...

Exponential function with 3 parameters?? Homework Statement A researcher suggests that the population, P, at time t can be modeled by P(t) = K / (1 + Le^(-Mt)), where K, L and M are parameters. Use technology to estimate and interpret K, L,and M. Construct the researcher's model using...

Homework Statement I have a frequency equation to solve for the displacement for a spring mass damper truss system, as seen below, [m]u''+[c]u'+[k]u=f(t), where m,c,k, are all matrices (2x2), and f(t) is a graph-defined forcing function. I am to use 3 nodes, using the central...

Homework Statement We have that for a crystal the lattice parameters (in angstrom and degree) are: a b c (in Angstrom) 10.5 10.5 10.5 \alpha β γ (in degree) 109.5 109.5 109.5...

hello :) let's look at the following functions: Langevin function L(x)=ctgh(x)-1/x Brillouin function B(x)=f(x J); when J→∞, then B(x)=L(x) to which I have the following questions: - how was the Brillouin function B(x)=f(x,J) developed? - are there other functions with the...

Hi, I've got a question about fitting a known function to a measured data. Suppose I want to find X parameters by fitting a curve to some measurments - What is the minimum number of measurements needed? Someone has told me that I need X+1 measurments, (because one degree of freedom), but...

i am buying Pulsed Laser Diode in Plastic Package 25 W Peak Power SPL PL90 and there is some parameters about semiconductors lasers... Forward current = 40 A why all this current ? then in the catalog Reverse voltage= 3 Volt then they say the Threshold current = 1A ? what is the...

In Euclidean three-space with coordinates (x,y,z) and line element ds^2 = dx^2+dy^2-dz^2 It is easy to show using the geodesic equation that: x = lu+l', y=mu+m', z=nu+n' where u is an affine parameter. However, is it possible to find a relation between l,m,n?

Homework Statement Solve using variation of parameters y''' - 2y'' - y' + 2y = exp(4t) Homework Equations Solve using variation of parameters The Attempt at a Solution I got the homogenous solutions to be 1, -1, and 2. So, y = Aexp(t) + Bexp(-t) + Cexp(2t) + g(t) I got...

The question I'm trying to solve is: y" - 6y' + 9y = \frac{exp(3x)}{(1+x)} I formulated the Gen solution which are: y1(x) = exp(3x) and y2(x) = xexp(3x) I've then calculated the wronskian to get: exp(6x) I then went onto to use the variation of parameters formula, which is where...

I am solving for the Y and Z parameters for the circuit below: For Y, I used the following equations by applying current sources at the terminals va is the node at the 2v1 dependent source (va-v1)/0.5 + (va-v2)/1 = -2v1 I1 = v1/1 + (v1-va)/0.5 I2 = v2/0.5 + (v2-va)/1 I got Y = [3 -2/3; 0 8/3]...

I just realized you can use variation of parameters (VOP) to solve for homogeneous 2nd order equations. I see it takes much longer to do so. But I was wondering why, if you use VOP, the u and v functions are 0. Is this because the coefficients of the homogeneous equation are constant, or...

Find the complementary solution of y^\left(4\right) + 2y'' + y = sint Homogeneous Form would be y^\left(4\right) + 2y'' + y = 0 r^4 + 2r^2 + r = 0 \rightarrow r(r^3 + 2r + 1) = 0 This is where I'm stuck. Once I find y_c(t) I should be able to finish the problem, but I'm having trouble at this...

Hello. I have three questions that I would like to ask.1. Could someone provide me with a resource containing examples of arbitrary parameters in theoretical physics. E.g. a modern example, yet to be varified, is dark energy. A historical example, one which has since been discredited, is the...

for the following circuit, i am trying to find the y parameters i have found y11, y12, and y22 to match the answer that my text provides, but i am having trouble with y21 the solution given is y11 = 1.5, y12 = -0.5, y21 = 4, y22 = -0.5 in trying to solve for y21, i get 4.5 this is...

Homework Statement I must solve (1-x)y''+xy'-y=(1-x)^2 knowing that y=x is a solution if the right hand side is 0. I must use this fact in order to obtain the general solution to the DE Homework Equations Variation of parameters? The Attempt at a Solution I'm looking at...

Please teach me this: Is it possible there are corresponding mass parameters for different types of interaction for a certain particle?.Because each type of interaction has an own contribution in total mass.Then considering quarks with electro-weak interaction,despite nonzero total mass of...

Homework Statement Measuring the flux of a star as a function of the time, the flux exhibit a decrease of 1.65% for 2h 56m, periodically every 57.22 days. Such decrease is ascribed to a planet transit. The continuous spectrum of the star is like a black body with T= 9500 K, and its...

I've picked up a bit more since my last problem. I need to solve the following DE: x^{2}\frac{dy}{dx}+x(x+2)y=e^{x} I decided to use variation of parameters, so I re-arranged it like so: \frac{dy}{dx}=\frac{e^{x}}{x^{2}}-(1+\frac{2}{x})y Then solved the homogenous DE...

Right now, my Achilles heel is a pokey DSL connection, but still, there is some software that I like to use that load quite slowly on my old PC. I have a Dell Dimension 8400 that must be 7-8 years old now, and I've been thinking about passing this one on to my neighbors' grand-daughters. They...

I need to find a solution to the following problem: (x^{2}-1)\frac{dy}{dx}+2y=(x+1)^{2} y(0)=0 I decided to try using variation of parameters. My teacher was unable to show any examples, and I'm having issues understanding the textbook. From what I see I need to get it onto this form...

I'm doing my economics thesis on game theory, and need to solve a system of nonlinear equations (these will be the reaction functions). Unfortunately, I have no idea how to solve it explicitly--indeed, I am a bit worried its impossible with the parameters. It is rather symmetric though. The...

Homework Statement Using the variation of parameters method, find the general solution of x^{2}y" - 4xy' + 6y= x^{4}sin(x) Homework Equations y_{P}=v_{1}(x)y_{1}(x) + v_{2}(x)y_{2}(x) v_{1}(x)'y_{1}(x) + v_{2}'(x)y_{2}(x)=0 v_{1}(x)'y_{1}(x)' + v_{2}'(x)y_{2}(x)'=x^{4}sin(x)...

Homework Statement Find a particular solution for these second order differential equations. Homework Equations 1) y''+9y=tan3t 2) y''+y=tan^2t The Attempt at a Solution I want to find a fundamental solutions y1 and y2 because I want to find a particular solution like this...