Parameters Definition and 535 Threads

Hi, I'm writing a term paper and am having a lot of trouble understanding what is meant by the real and imaginary parts of various quantities. It seems a lot of textbooks have their own conventions and it's hard to understand whether they've redefined some symbol when they "complexify" them...

Homework Statement I must solve ##y''+2y'+2y=e^{-t}\sin t##. I know variation of parameters might not be the fastest/better way to solve this problem but I wanted to practice it as I never, ever, could solve a DE with it. (Still can't with this one). Though the method is supposed to work...

x²y"(x)-3xy'(x)+3y(x)=2(x^4)(e^x) =>y"(x)-(3/x)y'(x)+(3/x²)y(x)=2x²e^x i don't know how to approach this problem because the coefficients are not constant and i am used to being given y1 and y2 HELP!

1. I need help understanding how to read the parameters from the stack and not from anywhere else. In addition, what is difference between reading from the stack and somewhere else? For example, if the parameters had this: logicUnit(unsigned long int value, unsigned long int flags, unsigned...

I just posted about the new parameters here: https://www.physicsforums.com/showthread.php?p=4152380#post4152380 Basically the new numbers look rather close to what Jorrie already put as the default in his calculator. zEQ looks familiar. Hubble rate 70 looks familiar :biggrin: Here's the...

the lines l2[/SUB and l3 are given by l1 : r = 10i + j + 9k + μ(3i+j+4k) l2: x= (y+9)/2= (z-13)/-3 l[SUB]3 r= -3i-5j-4k + λ(4i+3j+k) where mu and lambda are parameters. d) Show that AC=BC A(4,-1,1) this was given, I calculated and got B as (5,-1,-2) and C (1,-2,-3) This I...

Homework Statement Asked to find Weibull distribution parameters, \theta and \tau, using Excel's Solver feature. I know that the 25th percentile is 1500 and the 75th percentile is 250000. Homework Equations Weibull CDF = 1-exp(-(x/\theta)^\tau) The Attempt at a Solution I have...

Hi. I am doing a PhD atm and I have decided to take the plunge with gnuplot. I have fitted some data to an equation h(t)=ho+a(t-to)^b+kt, with a, to, b and k being fitting constants (empirical formulae describing creep behaviour of a compressed material with time). Does anybody know how I...

I'm trying to find the tri-linear interpolation parameters of a point C within a hexahedron of 3d vectors (C000, C100, C010, C011 etc) You could call this "inverse tri-linear interpolation" Ive used the same variable names as this wikipedia article...

Here's the proof that I read for method of variation of parameters- https://www.physicsforums.com/attachment.php?attachmentid=52267&stc=1&d=1351081780 What I couldn't understand is that how could one simply assume that u'1y1+u2'y2=0 and u'1y'1+u2'y'2=g(x) I just don't understand...

I wonder if TOE candidate theories (loop gravity, superstrings, twixtors, or <you-name-it>) predict from the first principles SM parameters (all, some of them, or some correlations like Koide formula)? If they don't predict SM parameters, then the only option is "10**500 different universes...

I was recently trying to prove the variation of parameters formula for an nth degree equation, and I have come up with a question about the assumptions made during the derivation. During the derivation we assume that: u1'y1(k) + u2'y2(k) + . . . + un'yn(k) = 0 for k < n-1. It leads to the...

Find a, b parameters such that the function such that the function $f(x)= (sin2x)/(a-bcosx)$ has extreme value in point (pi/3,1/4)

Homework Statement Given is a set of measurements with their respective errors for example an energy spectrum. In gnuplot one is to fit a function f(x;\{p_i\}) depending on a variable x and on fit parameters p_i. When the fit is done one gets values for the p_i with errors and a correlation...

Homework Statement A is a given 3x3 matrix A= \begin{pmatrix} a & 0 & 1 \\ 0 & a & b \\ 0 & 0 & c \end{pmatrix} a,b,c are real numbers 1) determine for what values of a,b,c the matrix A is diagnoizable. (advice: distinguish between the cases a=c and a≠c) Homework Equations...

Hello, I stumbled across the following equation in a presentation about collider physics: tcorrWV =(tiRV - tiWV) + (TOFRV - TOFWV), where tcorrWV is the corrected time for the wrong vertex, tiRV is the initial time of the right vertex, tiRV is the initial time of the wrong vertex...

Homework Statement see attached Homework Equations The Attempt at a Solution $$\eqalign{ & {V_1} = {Z_{11}}{I_1} + {Z_{12}}{I_2} \cr & {V_2} = {Z_{22}}{I_2} + {Z_{21}}{I_1} \cr & {\rm{ - - - - - - - - - - - - - - - - - - - - - - - - - - - }}...

Help please...Transmission line parameters in per unit hello there I'm trying to work on a program that converts electrical quantities of transmission line ( R , L , and C ) into per unit system using Matlab the thing is that I'm finding difficulties with the formulas , how I can obtain...

I read that conventional (low frequency) circuit parameters - voltage gain and power gain are not applicable for RF circuits but I didn't understand why? Can anyone please explain.

Hi dear friends, I am Maziar Bahiraee a chemical engineering graduate. I had a question about one of my last inventions and I found that friends this group are specialized in this field. Q: After a wave with specific parameters encounters an obstacle, which of the parameter(s) is changed and...

Homework Statement The Attempt at a Solution So I was wondering whether or not, in an instance of n observations and k explanatory variables, where the following is an accurate statement: That is, the estimate of beta_1 found by only regressing y on x_1 is equal to the the true multiple...

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...

Hello everyone. I am trying to calculate the focal points of the ellipse traced by a planet in orbit around a star, given the following known parameters: M_{sun} Mass of the sun r_{planet} Position vector of the planet from the sun m_{planet} Mass of the planet v_{planet} Velocity of the planet...

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...

Hi all, I'm performing an optimization of a mechanism composed of several planar four-bar linkage. I'm at a standstill in understanding which are the independent parameters for tracing a four-bar linkage mechanism in a specific configuration. Looking at this picture In my hopinion, the...

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 An object is influenced by 2 forces: environmental force F1 = 42 tons and a hydrodynamic drag factor F2 = 200 kN. These forces are directed against each other (one attempting to 'weaken' the other one). The corresponding mass of object is 10,112 tonnes. I am trying to create...

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...

Homework Statement Find the particular solution to t^2 y'' - t(t + 2)y' + (t+2)y = 2t^3 given that y1 = t and y2 = tet are solutions. Also, require that t > 0 The Attempt at a Solution Rewrite the original equation as y'' - ((t + 2)/t)y' + ((t+2)/t^2)y = 2t So first I calculate the...

Homework Statement Find the particular solution to t^2 y'' - t(t + 2)y' + (t+2)y = 2t^3 given that y1 = t and y2 = tet are solutions. Also, require that t > 0 The Attempt at a Solution Rewrite the original equation as y'' - ((t + 2)/t)y' + ((t+2)/t^2)y = 2t So first I calculate the...

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...

Homework Statement The distance between the nuclei Na and Cl is R_0=0.236 nm. The curvature of the potential energy is 109J/m^2. The potential of ionization of the Na is 5.1 eV while the electron affinity of the Cl is 3.65 eV. From these data, find the parameters a and \alpha in the...

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...

I am a 3rd year engineering physics student who is in a bit of a pickle. I underestimated the accuracy of a small (~1-5000) N-body simulation in terms of how realistic a dark-matter inclusive galaxy collision simulator would be with it. I now find myself being pointed in the direction of...

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...