Parameter Definition and 392 Threads

A parameter (from the Ancient Greek παρά, para: "beside", "subsidiary"; and μέτρον, metron: "measure"), generally, is any characteristic that can help in defining or classifying a particular system (meaning an event, project, object, situation, etc.). That is, a parameter is an element of a system that is useful, or critical, when identifying the system, or when evaluating its performance, status, condition, etc.
Parameter has more specific meanings within various disciplines, including mathematics, computer programming, engineering, statistics, logic, linguistics, electronic musical composition.
In addition to its technical uses, there are also extended uses, especially in non-scientific contexts, where it is used to mean defining characteristics or boundaries, as in the phrases 'test parameters' or 'game play parameters'.

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  1. P

    Java Java - What do parameter lists do?

    In class the other day, my professor had written this as part of the lecture notes: Thus, this definition was mentioned as part of methods. He then went on to show an example of this as in the following: public class Dog { private Collar _ collar; public Dog(Collar collar) {...
  2. J

    Height of an ellipse above the plane in three dimensions (z parameter)

    Homework Statement What is the expression for z (the height above the xy-plane) in terms of r,f,w,i. r = the distance f = the angle between the semi-major axis and the r vector w = the angle that the semi-major axis makes with the y-axis i = the angle that the plane of the ellipse makes...
  3. E

    Lattice parameter + valence + avg time between collisions

    valence Z=1, lattice param a = 4.05 conductivity = 1.76e7 . What's the avg time between collisions of a conduction electron in this metal (bcc structure).really have no idea lol
  4. S

    What is the Current Value of the Mass Parameter for Quintessence?

    Dear all, As u know, one of the best potentials for quintessence is V=[M]^[4+\alpha] [\phi]^[-\alpha] They usually call M, THE MASS PARAMETER. Who knows what is the value of M for now?
  5. K

    Why the Hubble Parameter Decreases to .85 of Today's Value

    Why will the Hubble parameter only decrease to .85 of today's Hubble parameter?
  6. P

    Consistent estimator for parameter from Rayleigh distribution.

    Welcome Using MLE I found that estimator \alpha parametr from Rayleigh distribution is described by formula \hat{\alpha}=\sqrt{\frac{\sum_{n}^{i=1}x_i^2}{2n}} but I can't proof that this estimator is consistent estimator. Would you be mind and help me with my problem.
  7. J

    Constant Hubble parameter -> accelerating Universe?

    Hi, Let us assume that Hubble's Constant H is really constant. Therefore: a' / a = H where a is the scale factor. The solution to this equation is: a(t) = exp(H t) This equation describes an accelerating universe with deceleration parameter q given by: q = - a'' a / a'^2 =...
  8. marcus

    What is the critical value of the Immirzi parameter in loop quantum gravity?

    It now looks like the Immirzi parameter has a critical value which is determined numbertheoretically, not by the Bekenstein-Hawking S = A/4. It used to be that with LQG the IP appeared multiplicatively in S = A/4 so that the value of the IP had to be ADJUSTED to get the S = A/4 equation...
  9. M

    Model parameter distributions from Gamma distributed data

    I have a set of data points {xi,yi} where each yi is a Gamma distributed variable where both the shape k and scale \theta depend on i. I then fit the data points with a power law model y=a(x)b. I would like to know the probability distributions for the fit parameters a and b. Is...
  10. A

    Parametric to Cartesian Conversion: Troubleshooting and Identifying Mistakes

    I have the parametric function x(t) = (1-t^2)/(1+t^2), y(t) = 2t/(1+t^2) and need to eliminate the parameter and find a Cartesian equation. I've tried to substitute t = tan u, then x(t) = cos(2u) and y(t) = tan(2u). From that I get y = sin(2x)/x. However, when I entered the original...
  11. N

    How to explain the smallness of mass while the mass parameter diverge rapidly in ?

    Please teach me this: How to understand the smallness of mass while the mass parameter diverge rapidly in renormalization group flow because the mass term in Lagrangian is the relevant operator.By the way,are there always exist the fix point of renormalization group flow in any QTF Theory,or in...
  12. N

    Optimizing Lattice Parameter (a) for Energy Efficiency and Temperature Control

    Hi... The variation of the total energy with increasing the lattice constant (a), the minimum value of the lattice constant correspond to what degree of temperature? Nawzad A.
  13. M

    Ginzburg-Landau Parameter for YBCO

    Can anyone provide a good reference which gives the G-L parameter for YBCO (a) along the ab-plane of the sample and (b) along the c-axis? I've been to the depths of Google Scholar and back and found nothing, so any help would be much appreciated. :)
  14. PainterGuy

    Are words argument and parameter interchangeable cs

    hello everyone, :wink: one short question. it is said function sqrt() takes argument inside the parenthesis. sometimes word parameter is also used. are they interchangeable? i am speaking in terms of c++. is int main() has any similarity to math functions such as f(x)=2x+7. but the problem...
  15. T

    Solving A2/15 B2/23 (Part ii) on Page 50 Cambridge Maths

    Hi, I am doing question A2/15 B2/23 (specifically part (ii)) at the top of page 50 here: http://www.maths.cam.ac.uk/undergrad/pastpapers/2001/Part_2/list_II.pdf I have done everything up to and including showing the impact parameter is given by b=h/E, but I am having trouble doing parts (a)...
  16. Physics Monkey

    Does the Immirzi Parameter Determine Black Hole Entropy in Loop Quantum Gravity?

    I would like to discuss a puzzle I'm wondering about in loopy approaches to quantum gravity. The puzzle is roughly as follows: The Immirzi parameter (IP) is a strange constant that appears in loopy approaches. Calculations of black hole entropy in loopy approaches seem to need to fix the IP...
  17. Z

    Regularization by differentiation respect to a parameter

    let be the integrals \int_{0}^{\infty}dxx^{2} (x-a)^{1/2}=I1 and \int_{0}^{\infty}dxx^{2} (x-a)^{-1/2}=I2 is then correct that I2= 2\frac{dI1}{da} whenever applying a regularization scheme , is it correct to differentiate with respct to external parameters ??
  18. H

    Basic T parameter table for RF design

    Can anyone tell me where I can find a basic T parameter table for RF design. One with the T parameters for shunt impedence in coaxial, series capacitance in coaxial, coaxial of length l etc...
  19. D

    Parameter range from complex inequality

    Homework Statement Hi Guys, I try to find the range for parameters phi1 and phi2 were the autoregressive process below is stationary. We have the process X(t)+phi1*X(t-1)+phi2X(t-2)=Epsilon(t) (1) Homework Equations We get the characteristic polynomial F(z)=z^2+phi1*z+phi2 (2) The...
  20. homology

    Introduction to order parameter fields

    Hi folks, I'm taking a class in statistical mechanics out of Sethna's text. Part of the course involves student presentations. I've settled on his chapter on order parameters, broken symmetry and topology. Its a relatively short chapter and I'd like to read some more. I'm looking for...
  21. marcus

    Maximum value of Hubble parameter (near start of expansion)

    An estimate of 0.94/tPlanck for the maximum reached by the Hubble parameter was given by Ashtekar and Sloan here (based on Loop qc): http://arxiv.org/abs/0912.4093 Loop quantum cosmology and slow roll inflation Abhay Ashtekar, David Sloan (Submitted on 21 Dec 2009) "In loop quantum cosmology...
  22. apeiron

    Initial value for hubble parameter

    Simple question hopefully. What was the initial value for the Hubble parameter immediately following the big bang (or ending of inflationary epoch)? I presume the initial velocity of expansion was lightspeed and started slowing from there.
  23. L

    Affine parameter Schwazschild

    Hi, I've heard it said that for Schwarzschild spacetimes, then the coordinate 'r' is an affine parameter for radial null geodesics in the region exterior to the horizon. It seems weird to me that one of the coords is an affine parameter. How can this be seen? I know that the radial null...
  24. P

    What Does the Dot Mean in a Function Like f(x,·,·)?

    When you see something like f(x,·,·), how are you supposed to interpret it? Sorry, I can't give example, the only places I've seen have been using it informally. I read, http://www.reddit.com/r/math/comments/995dl/ask_math_reddit_what_does_the_dot_in_this/ , but can't find a definitive answer.
  25. W

    Temperture Structure Parameter CT2

    I understand the physics behind the Temperature Structure Paramter, but need help find a intial value to divided by. Here what I am trying to do. dB = 10 log 10 (CT2/CT2i) What I need is an intial value (CT2i) for the temperature Structure Parameter for a monostatic sodar. The units need...
  26. J

    Real parameter given complex variable modulus

    Homework Statement Suppose z is complex number with |z| = 1 (also assume that z is not 1 + 0*i) Let z = a + b*i where a and b are real numbers. Find a real parameter, t, such that z = (t-i)/(t+i), where i = sqrt(-1) Homework Equations |z| = sqrt(a^2+b^2) The Attempt at...
  27. H

    About the order parameter in antiferromagnetism

    Hello everyone, As is known to all, the order parameter for the ferromagnetic case in the Landau expression is chosen as the magnetization. This is easy to understand. But for the antiferromagnetic case, what is the order parameter? People told me it was magnetic moment on the sublattice. But...
  28. L

    Did anyone done parameter extraction of metamaterial

    Hi I am trying to extract the parameters of the SRR metamaterial. i got very good result for the Permeability but not getting good enough rersult for permittivity , impedance and refractive index. is there anyone who is doing the same thing . we can exchange our code and help correcting each...
  29. stripes

    Impact parameter of alpha particles

    Homework Statement For alpha particles of 7.7 MeV, what impact parameter will result in a deflection of 2 degrees for a thin gold foil? Homework Equations impact parameter equation, b=\frac{kq_{\alpha}Q}{m_{\alpha}v^{2}}cot\frac{\theta}{2} The Attempt at a Solution Pretty easy, just plug...
  30. M

    Quick calculation of lattice parameter and unit cell volume for germanium?

    Homework Statement Calculate dhkl and vc for the (111) direction of germanium. Homework Equations dhkl=a/sqrt(h2+k2+l2) vc=unit cell volume=a1dot(a2xa3) or vc=structure form factor/density The Attempt at a Solution dhkl=a/sqrt(3) I know how to solve this, I've just...
  31. G

    Multiple integral with a parameter

    Let D be the following circle with the radius a. http://img580.imageshack.us/img580/6402/97833345.jpg Find the parameter a for which f(a) gets its minimal value. http://img844.imageshack.us/img844/2993/91289562.png
  32. D

    Equation simplifies if a certain parameter is small

    Hi folks, I have a differential equation which looks like sin(f) + \frac{1}{Q}\frac{d(f)}{dt} + \frac{d^2(f)}{d t^2} = g(t) Now for Q << 1 this should, according to our lecture, simplify to sin(f) + \frac{1}{Q}\frac{d(f)}{dt}}{d t^2} = g(t) Why that? I mean, obviously for Q<<1, 1/Q >> 1...
  33. T

    How parameter affects the roots of the equation.

    I have trouble figuring out this problem. If someone can help me out that would be appreciated. Suppose we have x^3 -x + C let r denote the largest root of the equation. What's a mathematical way of relating r and C? (quantitative). Also what's dr/dc Thanks in advance.
  34. C

    This is a lot to take in.Are the following models linear in parameters?

    Homework Statement Are the following models linear in parameters? If not, is there any way to make them linear-in-parameter mode?(The picture is in the attached) Homework Equations The Attempt at a Solution I tried to use dy/dx to show that they are not linear as the dy/dx is not constant...
  35. N

    How to Solve a Parametric Equation with Multiple Parts?

    Homework Statement So I'm given x(t)=4cos(t) and y(t)=sin(t). In a 4 part question, I 1st need to eliminate the parameter to get the equivalent rectangular equation, 2nd I need to find the slope of the tangent to the curve C-y(x) at t=1, 3rd find the times the tangent to the graph is...
  36. M

    Negative Schwarzschild mass parameter?

    I know that a Schwarzschild metric cannot have negative mass parameter. But what about regions? It is possible to have negative mass parameter between two spherical shells? If not, what is the argument?
  37. Q

    Stat mech problem on order parameter

    Homework Statement A system has a two component order parameter: [phi1, phi2]. The mean-field Landau free energy is E(\phi_1,\phi_2) = E0+at(\phi_1^2+\phi_2^2)+b(\phi_1^2+\phi_2^2)^2+c(\phi_1^4+\phi_2^4) where t, a, and b are positive constants. Represent the order paramter as a vector on...
  38. J

    Mathematica Plotting Parameter t vs. e1 Values

    I would like to generate a plot displaying the parameter t on the x axis, varying from 0 to 0.95 and the corresponding values of e1. My code below does what I want (I think) but is plotting all the different points on different graphs (all 950 of them!). How can I get it to plot on the same...
  39. D

    Find Parameter Set for N Intersections of 2 Implicit Functions

    Sorry for the wordiness of the thread title. Basically I'm wondering, if you have two implicit functions, F(x,y)=0 and G(x,y)=0 (typically rational functions with numerator and denominator very high degree polynomials), both dependent upon the same K (in my case > 34) dimensional set of...
  40. T

    Some slight confusion regarding the dimensionless Hubble parameter h.

    Hi, I am just writing up my MSc thesis and want to explain the dimensionless Hubble parameter that I have been using through my work. I understand that you take the valuefor the Hubble "constant" and then divide by 100km/sec/Mpc to leave get a value which has no units. There seems to be...
  41. A

    What is the difference between a parameter and a variable?

    It seems (to me) that parameters are also kind of variables in descriptions of physics. I am confused what makes a paramater different from a variable. Can anybody please explain this?
  42. tom.stoer

    Fractal LQG spacetime and renormalization of the Immirzi parameter

    Hi, this is not based on detailed work but just an idea which arised comparing causal dynamical triangulations and loop quantum gravity. In CDT it seems reasonable to treat spacetime as a fractal. That means there is no limit or minimum length in the triangulations, but the triangulations...
  43. O

    Efficient parameter estimation of marginal distribution

    hi all, the situation is this: i have a conditional PDF f_{X|(D,S)}(x|d,s) and the unconditional PDFs D and S, f_{D}, f_{S}. Now, I can marginalize the joint PDF f_{X,D,S}=f_{X|(D,S)}f_{D}f_{S} by integrating over d and s over their respective supports. What I'm really interested in is a...
  44. S

    Spiral and Disk Galaxies are controlled by single parameter. What and How?

    This is a significant discovery that something is fundamentally controlling and ordering the properties of spiral and disk gaseous galaxies. Elliptical galaxies have no gas and no star formation. The question is not only what but how is the unknown parameter controlling spiral and disk galaxy...
  45. J

    Anyone recognize this single parameter discrete probability distribution?

    I have a single parameter discrete probability distribution defined over the domain of non-negative integers with pmf in k of: Pr(k;L) = \frac{L^{k}}{k! * k! * I_{0}(2*\sqrt{L})} Where I_{0}() is the modified Bessel function of the first kind with order 0. I do know that E(k^{2}) = L...
  46. D

    Minimize parameter for Least Absolute Deviation LAD

    How to compute \beta = arg min_\beta \sum_{i=1}^N {|y_i - x_i^T \beta|
  47. L

    Unbiased Estimator for Gamma Distribution Parameter

    Homework Statement I need to show that c / (sample mean X) is unbiased for b, for some c. Where {X} are iid Gamma (a,b). Homework Equations N.A. The Attempt at a Solution I know how to show that (sample mean X) / a is unbiased for 1/b : 1) E(sample mean X / a) =...
  48. B

    How Does the Feynman Parameter Integral Relate to the Dirac Delta Function?

    I'm trying to show equation (6.39) on page 189 in Peskin & Schroeder. Homework Statement Show that \frac{1}{AB}=\int_0^1dxdy\delta(x+y-1)\frac{1}{(xA+yB)^2}. Homework Equations Defining property of Dirac delta function: \int_{-\infty}^{\infty}dx f(x)\delta(x-x_0)=f(x_0) Also...
  49. S

    Engineering Induction Motor, Parameter Test

    Homework Statement I just gave an exam where one of the questions was where I had to find the various parameters using the two forms of tests for an Induction motor: No load test Locked rotor. Now, I can do this question but there is one thing that is confusing me. I had to find the stator...
  50. W

    Rayleigh-Ritz Method and Distributed Parameter Systems

    Homework Statement Let me begin by saying that this will be a long post and will involve a few homework questions. I'm not looking for answers for per-say. Instead, I am looking to deepen my vague understanding of the Rayleigh-Ritz Method and how one can use it to find the mode shapes and...
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