What is Parameter: Definition and 392 Discussions

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. A

    Histogram fitting: fit parameter errors not corresponding with optimizer results

    Hi I'm having some big problems with some data! I will try to keep this as simple as possible... I have a random variable that admits a probability distribution that I have a fit function for. With a large enough number of samples I can get good estimates of the fit function parameters via...
  2. D

    Impact Parameter: Definition & Meaning in Physics

    I'm in a second year physics course, and were studying Rutherford scattering. I'm not having any trouble with the physical or mathematical concepts, I'd just like a more precise definition of the phrase "impact parameter". I searched google, and my notes and textbook but couldn't really find...
  3. J

    How to Eliminate the Parameter in a Set of Parametric Equations?

    Express the set of parametric equations x = E^t + e^-t and y = e^t - e^-t without using the parameter t. I really have no idea how to do this one. I tried substituting, and it just turned into a jumbled mess of nothing. Please help
  4. Fredrik

    Geodesic Tangent Vector: Affine Parameter Wald (p.41)

    Wald (p. 41) defines a geodesic as a curve whose tangent vector satisfies T^a\nabla_aT^b=0 . . . . . (3.3.1) Then he says that we could have defined it by requiring T^a\nabla_aT^b=\alpha T^b . . . . . (3.3.2) instead, where \alpha is "an arbitrary function on the curve", but we...
  5. H

    What is the Lattice Parameter c of an HCP Crystal Structure?

    Homework Statement I'm trying to figure out the lattice parameter, c, of the HCP crystal structure. Here are a couple links showing the structure...
  6. H_man

    S11 (scattering parameter 11) of a Resonator?

    If my resonator is shorted at one end and has a partially transmitting grid at the other end is it correct to use S and T parameters to build a model of the device? I ask this as the first few sentences of the Wikipedia article on S-parameters states that a matched load should be placed at...
  7. R

    Marginal Distribution of X w/ Lambda Parameter: Probability Help

    I am a little shaky on my probability, so bear with me if this is a dumb question... Anyway, these two random variables are given: X : Poisson (\lambda) \lambda : Exponential (\theta) And I simply need the marginal distribution of X and the conditional density for \lambda given a value for X...
  8. C

    When we use arc length as a parameter

    If we have a fly in a room, its position respect to some frame of reference will change with time, so if we want to describe the fly's movement with a parametrized curve, it is easy to see the convenience of taking time as the parameter. I read that we can also take the length of the curve as...
  9. N

    Calculating error in fit parameter

    I'm working on an experiment and trying to do some data analysis which seems to me should be fairly trivial, but I can't for the life of me figure it out. I want to know the value of some property A and to do so I'm measuring data points (x,y), which are related to the value I want by A =...
  10. D

    Hubble's constant and decelaration parameter

    Homework Statement I've been measuring hubble's constant by calcultaing the redshift on a star and it's distance from Earth using a simple method of assuming galaxies have a standard size, then measuring their apparent size to gauge their distance away. To refine the model i have been asked...
  11. L

    What is the solution for a matrix with a parameter in its determinant?

    Homework Statement Hello all, I have a parameter x of a matrix M = [21, 7 14, 7] the determinant of |(M - xI)| = 0 Homework Equations I is known as the identity matrix The Attempt at a Solution My solution seems to be a bit...
  12. J

    What is the variation of parameter method for solving differential equations?

    Homework Statement (D^2 + 2D + 1)y = ln(x)/(xe^x) Homework Equations D = d/dx The Attempt at a Solution First I find the roots of the left side of the equation, -1 of multiplicity 2. This leads to y(c) = Ae^(-x) + Bxe^(-x) Substituting A and B with a' and b' and dividing...
  13. D

    Expansion in a Small Parameter

    When an expression is derived using an "expansion in small parameters," what do they generally mean? I am not too familiar with this term, and the only thing I can think of are Taylor expansions. I have seen expressions that contain functions of these parameters, and after the expansion in...
  14. R

    LaTeX Increment (or decrement) a parameter in LaTeX

    How can I increment or decrement a parameter in LaTeX? For example, suppose I create an environment foo as follows: \newenvironment{foo}[2]{\begin{tabular}{*{#1}c*{#2}r}}{\end{tabular}} I can write \begin{foo}{4}{3} <tabular data in seven columns> \end{foo} But in my...
  15. C

    Derivative of Log Determinant of a Matrix w.r.t a parameter

    Hi, I'm trying to see why the following theorem is true. It concerns the derivative of the log of the determinant of a symmetric matrix. Here's the theorem as stated: For a symmetric matrix A: \frac{d}{dx} ln |A| = Tr[A^{-1} \frac{dA}{dx}] Here's what I have so far, I'm almost at the...
  16. U

    Pleasse Help Me to Find Parameter of CIrcle by integration.

    please help me to findout this problem i am putting this question second time bcoz i was unable to findout its category i am new here answer should be 2(pi)a
  17. N

    Calculating impact parameter

    Homework Statement I'm trying to plot the trajectory of a photon near a schwarzschild black hole. I have the equation for the trajectory but I'm stumped by the impact parameter and cannot find out how to calculate it. Homework Equations \frac{d\phi}{dr} = \pm \frac{b}{r^{2}\sqrt{1 -...
  18. P

    Motor controller acceleration parameter

    Hey all I'm using a controller from MVP. The guide for the controller is located here: http://www.micromo.com/servlet/com.itmr.waw.servlet.FileViewer?sprachid=1&kid=42044&pid=531688&fid=531711&kdid=40929" . The controller's attached to a motor with a 2000 quadrature shaft encoder. I can get...
  19. J

    Range of the parameter of sphere intersecting with a plane

    Homework Statement Find the range of the parameter d for which the intersection of the sphere x2+y2+z2=1 and the plane x+y+z=d is non-empty. Homework Equations Cartesian coordinates of a sphere: x=rcos\thetasin\phi y=rsin\thetasin\phi z=rcos\phi r=1 The Attempt at a Solution...
  20. J

    Minimum separation, impact parameter, and scattering angle

    Homework Statement Alpha particles of kinetic energy 9.6MeV are incident on a silver foil of thickness 7.0 micro meters. For a certain value of the impact parameter, the alpha particles lose exactly half their incident kinetic energy when they reach their minimum separation from the...
  21. P

    Integration by Differentiating with Respect to a Parameter

    Homework Statement Consider I = \int^{1}_{0} \frac{t-1}{ln t} (No, the problem does not contain a dt at the end of the integral, but I'll assume its a typo) Think of the t in t-1 as the a=1 limit of t^a. Let I(a) be the corresponding integral. Take the a derivative of both sides...
  22. A

    DE equation of state parameter

    Homework Statement Plot \Delta w as a function of spectroscopic redshift for some given biases between spectroscopic and photometric redshifts. Homework Equations \Delta w = \frac{\partial D_{A}}{\partial z}\frac{\partial w}{\partial D_{A}} \Delta b D_{A} = \frac{c}{H_0} \cdot...
  23. P

    Range of Nordheim parameter y

    Hi, The current density due to field emission on a surface is described by the Fowler-Nordheim equation J = t(y)^{-2}a\phi^{-1}F^2\exp(-v(y)b\phi^{3/2}/F) where v(y)=1 - y^2+ (1/3)y^2ln y and y=cF^{1/2}\phi^{-1} F is the applied electric field above the surface. (See for example...
  24. T

    Order parameter, correlation function and length

    Hello people, I don't understand the relation between those concepts, I tried to read what's written in wikipedia about them but no use. Can someone please elaborate more about the relation between them in some intuitive manner? Thank you :)
  25. Battlemage!

    Basic Calculus III- Arc Length Parameter and Length- Getting a negative length

    Homework Statement Find the Arc Length Parameter along the curve from the point where t = 0 by evaluating the integral: s = ∫ |v(τ)| dτ from 0 to t Then find the length of the indicated portion of the curve. Homework Equations The vector I am using for this: r(t) = (etcos t)i + (etsin...
  26. N

    Elimintate the parameter problem

    elimintate the parameter 1. x=lnt y=t^(1/2) e^x=t y=e^(x/2) 2. x=2t^3 y=1+4t-t^2 for slope = 1 dC/dt=(4-2t)/6t^2=(2-t)/3t^2=1 3t^2+t-2=0 t=-1 t=2/3 A(-2,-4) B(16/27,29/9)
  27. S

    Convert Continuous Inverse Scale Parameter to Physically Relevant Units

    How to convert a continuous inverse scale parameter into a physically relevant quantity: 1) What is a CISP, and why is called continuous and why inverse? 2) how do I deal with it: Example: On http://www.apec.umn.edu/faculty/gpederso/documents/4501/risk45DistFunc.pdf the error function is...
  28. K

    Value of Hubble Parameter in Decelerating Universe

    what was the value of the Hubble parameter when the universe was decelerating?
  29. P

    Fundamental parameter probabilities

    What are the odds that any particular big bang will result in the 20(?) fundamental parameters having the values that will allow life to form?
  30. A

    Confidence Interval for a function of a parameter

    How would you find CI for some function of a parameter? the case I'm particularly interested in is an approximate CI for p^2 where p is the proportion in the binomial model. http://en.wikipedia.org/wiki/Binomial_proportion_confidence_interval
  31. S

    Is there any need to introduce time as a parameter?

    is there any need to introduce time as a parameter? is there any meaning of time, without any velocity? time is because of some change and that change can be measure by position only. so why is there an unnecessary extra parameter (time).is there any need to measure a rate of change with...
  32. V

    Atomic Radius Problem with 286 pm Lattice Parameter

    i have one problem on atomic radius. i read (http://en.wikipedia.org/wiki/Atomic_radius) the artical and try to understand it but i don't found any formula for it. The problem is: if the lattice parameter of alpha iron is 286 pm (Pico meter),what is its atomic radius? here we have only one...
  33. G

    Parameter determination permanent split capacitor motor

    Magnetic saturation seems to have a lot of influence on parameter behavior during load test on permanent split capacitor motors. Is there a method to integrate saturation in the equivalent circuit calculations . Is this possible when one uses the classical tests DC-test, Blocked rotor test, no...
  34. F

    QCD \Lambda Parameter: Definition & Its Role in Non-Perturbative QCD

    I have a simple sounding question about QCD and its scale parameter \Lambda: The general consensus amongst field theorists is that QCD is not a well defined theory by its Lagrangian and the quantization procedure alone. One needs an additional parameter \Lambda, which sets the scale of...
  35. R

    Parametric - Eliminating the parameter

    Homework Statement http://mathbin.net/equations/8457_0.png My result does not seem like a "valid" equation. Is there any other approach I can take or anything that I can do to make it look prettier? Thanks.
  36. K

    What is order parameter and how to find critical temperature?

    I am reading some material on phase transition. In those, they use order parameter quite a lot, but what is order parameter? What's the physical significance of it? If I got the free energy , which involving order parameter m, how can I find the critical temperature?
  37. O

    How to solve the Free Parameter Problem in SUSY ?

    How to solve the Free Parameter Problem in SUSY ?? In Standard Model, we have 19 free parameters: me Electron mass 511 keV mμ Muon mass 106 MeV mτ Tauon mass 1.78 GeV mu Up quark mass () 1.9 MeV md Down quark mass () 4.4 MeV ms Strange quark mass () 87 MeV mc Charm quark mass...
  38. A

    What is Quench Parameter? & Where Does it Apply?

    Could anybody tell me what is so called Quench Parameter ? And where is that parameter applys into? Thanks a lot! :smile:
  39. J

    Signal processing + parameter estimation

    Is parameter estimation in DSP concerned with things such as bit error rates, maximum likelihood detection etc ... ? If not, can someone point me in the right direction so I can find some learning material. thanks
  40. O

    Very Basic Question (One Parameter Family Question)

    Homework Statement Construct a One-Parameter Family of implicit linear two step methods of greatest possible order. Homework Equations \alpha1 yn+1 + \alpha0 yn = h (\beta0 Fn + \beta1 fn+1) I've attempted a solution, but my question isn't involving it. I'm having a major brainfart...
  41. H

    How do I convert a parametric equation to cartesian form for calculus analysis?

    basically i need to convert the following parametric equation: x=a cos (T) + b cos (T/2) y=a sin (T) + b sin (T/2); where a and b are coefficients to cartesian form: y = f(x) i need it in that form so i can do calculus analysis for an improved engine design i hope to develop. thanks...
  42. T

    Is There a Parameter a Such That f(x) Equals ax for All x?

    f(x) is a continues function on (-infinity,+infinity) for which f(x+y)=f(x)+f(y) prove that there is parameter a for which f(x)=ax for every real x i was given a hint to solve it for x in Q there is no much thing i can do here for which i can use theorems the only thing i am given...
  43. B

    Variation of Parameter Problem

    Homework Statement Find the general solution using the method of variation of parameters of: y''-6y'+9y=(x^-3)(e^3x) I found the roots of the corresponding homogeneous equation to be lamba = 3. So there are repeated roots. My question is, how do I solve a variation of parameter...
  44. S

    Poisson variable w/ uni. dist. parameter

    Homework Statement Let X\sim Poi(\lambda) and assume \lambda\sim Uni(0,5) Q: Find \mathbb{P}\{X \geq 3\}Homework Equations For a Poisson r.v. with parameter lambda, \mathbb{P}\{X = k\}=\frac{\lambda^{k}e^{-\lambda}}{k!} and the probability that lambda is in the interval (0,5) is 1/5 and 0...
  45. T

    Continuety parameter question

    i tried to solve it but i didnt get any parameter value ?? http://img403.imageshack.us/img403/5395/25739192yz6.th.gif
  46. D

    COMSOL - parameter dependent eigenvalue calculations

    Hello, I am using COMSOL (RF modul) for some time now to calculate the eigenvalues (modes) of optical fibers. So far I changed all the params from hand in the software. But it is getting anoying to change a parameter (the wavelength) and to recalculate if one wants to calculate for many...
  47. M

    Changing the running parameter

    hi there! I have the following sum: \displaystyle{\sum_{n=1}^\infty}(-1)^n\frac{(2z)^n}{(2n)!} and I want to let it run from n=0 to infty it´s somehow obvious that: \displaystyle{\sum_{n=0}^\infty}(-1)^n\frac{(2z)^n}{(2n)!} -...
  48. S

    Standard gravitational parameter

    Hi, Is it true that the standard gravitational parameter of an object (G*M) is more accurately known than the the gravitational constant (G)? If so, why? Any references would be much appreciated. Thanks, San
  49. O

    What is the relationship between impact parameter and billiard ball collisions?

    Homework Statement My problem has to do with impact parameter of two billiard balls. I don't want my problem solved persay, I just want to understand the problem, as I have a few things I am unclear about. If impact parameter is what "would've been the distance of the closet approach of the...
  50. A

    Can time be a function in any parameter?

    It is the question ,I had posted some threads but i couldn't clarify my idea but now i came with the question . Can time be T=f(p) ?
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