Fitting Definition and 242 Threads

Hello PF, Ok so here is my problem. I have an array of data points which are the chi^2 values for a fit I have performed. I wish to calculate the 1-sigma error for this fit, so I figure I could find the lowest chi^2 value, and the two points either side that value, and fit a quadratic...

Universal joint/ball bearing... controlled rotating arm for a furniture fitting Hello forum, I need your help on a furniture project we are developing in the office. its basically a floor standing lamp which needs to have a user regulated rotating arm. We are right now looking at different...

Hi everyone, I want to find a function to fit a two arrays data (X,Y=f(X)) with high precision, but I am not succeed. Can anyone help me. These are my data: X={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32...

Homework Statement For the given set of data, find the least-square curve: A) f(x)=Ce^Ax, by using the change of variable X=x, Y=ln(y), and C=e^B to linearize the data points. B) f(x) = 1/(Ax+B), by using the change of variable X=x and Y = 1/y to linearize the data points. x : [ -1 0 1...

"Shape preserving" fitting algorithms Does anyone know if there is such a thing as a "shape preserving" fitting algorithm? Now and then I run into the following problem: I have a set of rapidly varying data and try to fit it using an equation with e.g. 5 unknowns; I know that I can make it...

Hi, I'm posting this in this particular forum because, though this's a statistics question, my application is in high energy. My question is regarding a problem in Bevington's book (Data Reduction and Error Analysis..., Page 193, Ex. 10.1), but I'll give a general description here... Say...

Dear All, I have received 2D drawings of Tube Fitting Parts. I need to create the model and assign the properties. I like to know how to assign the end styles for different Tubing Parts and how to define the connector (tubing) points. Any help is highly appreciated. Thanks in...

Homework Statement Given: clear n = 100; x = 1:n; err = randn(1,n); mean(err); std(err); y = x + err; cftool Q - Relate your fitted to the data in y to the mean, S and SE values. You should also compare the fit results to the 95% point on the curve of the integral of the normal...

Hi! I know the value of a function f and its first and second derivatives at different point r (1D). I know how to fit it using only f(r) and r, but I'm sure its is possible to improve the quality/speed of the fitting by using also f'(r) and f''(r). Is anybody have in mind a fitting algorithm...

Hi everybody, I hope to find someone can help me, What are the equations of linear fitting? Are my equations right? n.Er + R-\sumI =\sumV \sumI.Er + R \sum(I.I) =\sum(IV) Please help me I need it today.:cry: If there is any website can help me please put it here:confused:

I recently completed an experiment for university level physics and am currently doing the analysis of the data. This data has been transformed to fit a linear model and it fits this very well, with the line of best fit lying within all error bars. I need to provide estimate of the gradient...

I'm currently working on a MATLAB program which, given two sets of data each representing curves, will transform (through rotations about the origin and x-y shifts) the first curve so it fits the second one best (so far in terms of sum of squares). I have been able to create a program...

Hi all, At the moment I am trying to find a best fit equation to radial velocity data vs. time of a planet HD17156b. The paper with the Authors fit parameters (I am trying to mimic the fit) has the arXiv ref number of :0704.1191v2 From this paper I extract their data, which is on the final few...

hi, there my question is let's suppose we have the magnetization (M) versus the applied field (H) as M(H,T)= \sum _{n=1}^{N} W(x_i ) (x_i ) Lang (H.A.x_{i}/T) here 'A' is a constant 'T' is the temperature of system Lang(x) is the Langevin function coth(x)-1/x , My problem is how to...

hi, there my question is let's suppose we have the magnetization (M) versus the applied field (H) as M(H,T)= \sum _{n=1}^{N} W(x_i ) (x_i ) Lang (H.A.x_{i}/T) here 'A' is a constant 'T' is the temperature of system Lang(x) is the Langevin function coth(x)-1/x , My problem is how to...

Customer of mine is wanting me to confirm that a hydraulic fitting I am selling him will withstand 800F. The fitting is a standard issue hydraulic fitting (#12 BPP Female Coupling) that will be welded to 6" SHD 80 pipe. The pipe is on the exhaust side of a diesel engine onboard a cruise ship...

Hi, I've just been trying unsuccessfully to fit a polynomial to a large set of data in Matlab (1301 points). I want to fit a polynomial to the data so that I have a function with which to try and manipulate the data in different ways. I have no problem fitting polynomials to much smaller sets...

Hi all, I am attempting to find the best Keplerian fit to the Radial velocity data vs. Time such as this plot: http://austral.as.utexas.edu/planets/hd37605/hd37605.html I was wondering whether anyone could suggest some freeware that might be able to help me out. Any information would be...

Let's say I have some data, as a function of a variable x. I want to fit this to the real part of the function \frac{A}{1-ix}\left(1+\sum_{n=1}^\infty\frac{c_n}{(1-ix)^n}\right) by numerically fitting the first N of the c_n's (A is fixed). I tried something like A = 1; N = 100; fit...

Homework Statement I have made an experiment with a Hall-meter and I have got some data. I know have an expression on the form B(a) = \mu IN\frac{{a^2 }}{{2\left( {a^2 + z^2 } \right)^{\frac{3}{2}} }} where z = 0.02 m and a is my only parameter varyring. I have plottet these data, and I...

Hi there, This might be a sort of vague question, but if I have a plot say that I don't know the data points for, how can I go about trying to find a fitting function (basically a functional form) for the curves I'm looking at? Basically I have a figure I got from a journal paper that I want to...

Hey I need to use the Least Square Fitting approach to calculating the best line of fit. I have read loads, and can't seem to figure out how to get passed the Inverse matrix part? Anyone know any good links, or can guide me on how to do least square fitting? Thanks

Homework Statement I have an equation as a function of time. (eq1) C(t) = Css + a(e^.5t) + b(e^.9t) t>0 Where, Css is a constant. then I have 6 data points of time and C (Concentration of a liquid) 1. I have to find an equation to find the maximum time and contains a, b and Css...

I have measurement dataset (x_i,y_i) -pairs with error for each value \Delta x_i and \Delta y_i so that I can plot datapoints with vertical as well as horizontal errorbar. I want to fit linear regression line y=a_1 x + a_0 and also error lines to the data. But how I take into account as...

hi, I am trying to do a curve fitting for a waveform obtained from the division of 2 FFT data. So, I used invfreqz in Matlab so that I can obtain the transfer function of the waveform, and at the same time, find an estimated waveform for the curve obtained. However, I can't seem to do it...

This should be easy but I've not done this in years and I'm feeling dense: I need to fit a quadratic curve to three constraints, two of which are points, the third is an angle. I've found examples to do this but only if all three constraints are points, so if someone would kindly explain...

I have a set of data and I need to fit a curve to it. The equation of the curve is: y=20-a*10*log(x) My problem is just getting a curve fit to this equation. What function in MATLAB should I be looking for? How do I get the value of 'a'? Is it easier to achieve this in Excel? How?

Homework Statement A hot wire is placed in a region of mass air flow. There is a current on the wire causing it (wire) to heat up. The current is regulated such that the wire temperature is constant. Measurement of current on the wire is related to the mass airflow by King's Equation...

Homework Statement An experiment was conducted on a liquid at varying temperatures and the volume obtained at the differing temperatures are as follows: V/cm3 θ/oC 1.032 10 1.063 20 1.094 29.5 1.125 39.5 1.156 50 1.186 60.5 1.215 69.5 1.244 79.5 1.273 90 1.3 99 Assume that V...

hello having a set of points of a curve, how i can find the best quadratic bezier curve that fits this curve? (so we have start and end points of bezier curve, and only the position of control point is required.) THX.

I have a set of data points relating the width of an object in an image to its distance from the camera. I'd like to find the simplest curve that fits "pretty well". When I graph the points, it looks like a hyperbola would be a good fit. Is there a simple iterative method to find an equation...

Does anyone know how to fit a cubic Bezier curve to a given set of data points? If so, I'd appreciate some coaching on the methodology. Bezier curves have separate equations for x and y in a parametric variable t that varies from 0 to 1: x = at3 + bt2 + ct + d y = et3 + ft2 + gt + h...

Hi, What is Banjo fitting?(In Aerospace) Application of it?

Hello, I have a problem I need to solve quickly... basically, I have a set of points in 3D space that make up a straight segment of a nanotube, and I want to "bend" the points along a circle (to simulate what happens if you bend a nanotube into a torus). I basically want to do to all of my...

I'm almost too embarrassed to post, but I thought someone might have insight that could help me here. I'm trying to fit an equation to data, but I'm just not sure what sort of equation I should use. I have some requirements on the form of the equation, and then I have points (yet to be...

If I know 2 points in the +x,+y quadrant, and I want to find the f(x) = a -------- (b*x)^2 curve that passes through both points (a and b are constants). This is probably either really simple or impossible. :rolleyes:

I am seeking a function r=r(\eta) for a computational mesh. It has to have the same shape as the one shown in the figure attached. This figure has been achieved via polinomical approximation, but it doesn't give me many chances to change parameters of contractions. Maybe there is an analytical...

Gday, This is a very simple question and it should only take one sentence to answer. It's not worthy of these forums, lol, but despite my efforts I cannot find an answer through google. If a light fitting says '40 watt max' and I stick a 60 watt bulb in it, will that have any adverse...

I'm a web developer working on a bit of javascript code for a personal project. I took through Calc II and linear algebra in college, but haven't looked at any of it a couple of years, so I'm a little rusty on the details. Anyway, what I'm trying to work out is a way to scale/transform an...

I have two polynomials fit to two different sets of data points. What I need to know is if there is a way to obtain a polynomial such that it will minimize the distance between all the points on both the other polynomials?

Guys.. Does anyone know where to find really slim fitting suits? (male)

Hello, I'm writing some code that will check if an array of products with given dimensions (length, width, height) can fit inside of a shipping box of given dimensions (length, width, height). Is there an algorithm to do this, or could someone point me in the right direction of where to go...