Fitting Definition and 224 Threads

Homework Statement I'm told that someone goes for a walk on some cliffs and given data for the total time of the trip and the distance traveled and the maximum height difference during the walk. I'm asked to find a function for T(d,h) i.e. time taken as a function of distance and max height...

Hello. This is 2D with arbitrary orientations. I have a quadratic curve segment defined by 2 end points and another one in between. I can find lots of other points along this curve. I want to find a close-enough elliptic spline. It is defined by 2 end points and the point of intersection...

Are there any programs which could be used to fit the Supernova data to constrain the cosmological models's parameter? thx

Hi. I have a set of samples with small white gaussian noise that form a small part of an ellissoid in 3D space. I'm looking for a way to find the center and the axes directions of the ellipsoid that best fits these samples. This is an overdetermined problem with much more 3d points than...

I was wondering if anyone could help me with this, I've been trying to curve fit Young's formula for double slit refraction: =Io*sinc(alpha)^2*cos(beta)^2 alpha=a*sin(theta)*Pi/wavelength beta=b*sin(theta)*Pi/wavelength with a and b as the parameters I'm trying to find. I've been...

We have been trying to fit experimental diffusion results to the diffusion equation using Matlab to evaluate the Diffusion coefficient. The equation we used: y=C*erfc(x/(2*sqrt(D*t))) Experimental values [x],[y] and t are given. C and D are to be evaluated from the curve fit. We used cftool of...

Okay, here's a problem that I've been struggling with for a few weeks. I'm conducting a series of measurements, where I get two sets of data, i.e. one xdata value gives me two ydata values. I want to curve fit the two data sets to two different functions, F1 and F2, that depend on the same...

hi, i make use of the r-square values quite extensively in my modeling work, mainly as an indicator of the 'goodness of fit' between data and linear/exponential models. however, i have often been told that r-squares are not rigorous indicators, especially so in cases where there exists...

Ok, so here's a weird problem. I am trying to make a 1/4 npt fitting with two pieces of brass pipe. The tap says: Vermont 1/4 NPT 18 HSGG M21 The die says: 1/4 NPT Baystate -5 So I threaded the pieces of pipe, expecting them to fit together nicely... and they didn't - far from...

Hello, I am constructing a MATLAB script to tightly pack an arbitrary given geometry with spheres of a predefined radius. Coordinates of the vertices of the geometry (a polyhedral model) are given; I am thereby developing an algorithm to plot/track all spheres that fit within the boundaries...

[b]1. This is the given data table --------Jan----Feb----Mar---Apr----May----Jun----July----Aug----Sept----Otc----Nov----Dec Maximum:33.2--32.2--31.2--28.9----25.4----22.2--21.9----23.9----27---- 29.8----31.7----32.9 This is a temperature table and i need to find its sine equation.b3/ y=...

Hi Math Experts, I have a two part question: Let's say I have a set of data and I want to fit a distribution to it, but I have to get rid of all the data below some threshold value, so that a large part of the left side of the histogram is cut off. How would I go about fitting a distribution...

Homework Statement Suppose (Y1, Y2, Y3, Y4) = (5.2, 6.8, 11.9, 17.0) are the average yields (in tonne/ha) of potato grown in soil with 4 different levels of superphosphate fertiliser, x1 = 1.20, x2 = 1.75, x3 = 2.30, x4 = 2.85. We want to fit the model E[Yi] = \beta1 + \beta2xi + \beta3zi...

Hi, I have a DC motor that have these dimensions: http://www.micromotorssrl.com/motor_l149/L149.pdf and the problem that i have is to make the "D-hole" in a solid 6mm steel shaft. At the bottom of the hole i was planing to put a neodymium magnet so that you easily could remove and put back...

Homework Statement Using a simple "trick," you can find a polynomial function whose graphi goes through any given set of points. For example, the graph of the following function goes through the points (1, 3), (2, 5), and (3, -1). f(x) = 3\;\frac{(x-2)(x-3)}{(1-2)(1-3)} \;+\...

I have this residual vs fitted values plot in R, and it should show a scatter of points with constant variance and mean 0. The mean 0 part seems to hold, but there is quite a clear diamond shape for the variance... I have tried raising the response variable to a power <1 and a log...

Homework Statement I need to fit a curve using cosh to a hyperbola with a vertex of (0,0) and a point at (4,7). The scanned worksheet can be found here http://img519.imageshack.us/i/scan0001gu.jpg/" http://img192.imageshack.us/i/scan0002uz.jpg/" Homework Equations y=a cosh...

Homework Statement Is there a good way to do a fit. The fft looks simple: I am trying to fit data from my experiment to the very nonlinear nested sine function given as equation 3 here: http://www.physics.umd.edu/courses/Phys375/HillSpring10/Labs/Lab5Diffraction.pdf Homework...

Hey guys I'm completing an experiment and I'm required to extrapolate data by performing nonlinear curve fitting. I have 3 sets of data: (x1, y1); (x2, y2); (x3, y3). I'm required to fit the above mentioned sets of data to the following equation ...

Hi, I am trying to fit a prony series to set of data(modulus and time). I want to use curve fitting to fit the experimental data set. I am confused about the time constants. Is there a way I can find the time constants without having to do it by hit and trial method. Is there a way by which I...

hello, is there any curve fitting software for free for linux user?? I know only gnuplot..is there some more software..? something similar to igor or origin or sigmaplot... Or these scientific fitting software are only available for windows?? please reply me about your free software, which you...

I have to fit a resonance curve to my data points, where the equation for the curve and the data points are: model = a/Sqrt[4 k w^2 + (v^2 - w^2)^2] data = {{242, 7/10}, {244.3`, 1}, {245.33`, 3/2}, {245.54`, 2}, {248.63`, 4}, {249.6`, 5}, {250.48`, 34/5}, {250.91`, 8}, {251.18`...

1. Homework Statement Suppose two variables x and y are known to satisfy a relation y=Bx. That is a graph of x vs. y is a line through the origin. Suppose further that you have N measurements (xi,yi)and that the uncertainties in x are negligible and those in y are equal. Prove the best...

I = I_{L} - I_{0} \left\{\exp\left[\frac{q(V + I R_{S})}{nkT}\right] - 1\right\} - \frac{V + I R_{S}}{R_{SH}} The above equation represents the curve that I would like to fit my data to. However, 'I' is dependent on 'I', should I do this with a series?

so i have the equation attached which i want to solve for a,b and Co. Tk is a time, and k is a whole number above 0. Using an iterative non linear method i need to solve for a,b and Co. I have heard of the Levenberg-Marquardt method, but it is quite complicated, and I wondered whether there...

I have a set of points and I want to find a "best fit quardric surface" through the points. I did the following: 1) Assume the function is in the form: a x^2 + b y^2 + c xy + d x + e y + f = z 2) Make a nx6 matrix of the points put into (1), that is A=: x1^2 y1^2 x1y1 x1 y1 1 x2^2 y2^2...

Hi I have fitted Gaussian function to some data in matlab. Now MATLAB gives me this: General model Gauss1: f(x) = a1*exp(-((x-b1)/c1)^2) Coefficients (with 95% confidence bounds): a1 = 2633 (2628, 2637) b1 = 1824 (1824, 1824) c1 =...

I have a set of data for an absorption spectra that I plot the firtst derivative of and it gives me a gaussianish plot, I then want to fit it with a gaussian and what I've been doing so far is calculating the mean and variace of the spread and then using them in the equation. Although this does...

Hi, Given that the radius of a circle is X, and the side length of a square is Y, what is the maximum number of squares you can fill inside this circle, provided that the squares do not overlap? If you know of a general formula or something, can you please tell me the proof or give me a link...

Hello, I am trying to figure out how to fit a plane passing through the origin in \mathbf{R}^3, given a cloud of N points. The points are vectors of the form (x_1^{(k)}, x_2^{(k)}, x_3^{(k)}) , where k stands for the k-th point. I want to minimize the sum of squared distances point-plane. What...

I have a problem at work! We have a large annulus that we need to fit a shaft into. I have calculated the tonnage required and it is outside of our workshop facilities. Any ideas, Lub, etc?

Homework Statement I had to do a curve fit on some data and got an equation to the form:Homework Equations F(t) = a_0 + a_1 t + a_2 t^2The Attempt at a Solution Each parameter has an associated uncertainty. I need to integrate F(t) over a range to get I. How do I find the the uncertainty in...

I am graphing Potential(Volts) y-axis vs distance (r) x axis. I am asked to fit a power function F(r)=Ar^n . Any ideas on how to do this? What is n supposed to represent?

Homework Statement Given some data set, (x,y), fit to the the curve y=bx^2+a by minimizing the square of the deviation. Preferred to use matrices. Homework Equations The deviation for the ith data point is simply: d_i^2=(y_i-y)^2=(y-bx_i^2-a)^2 The Attempt at a Solution If I understand...

I've run into these formulas many times but I've never seen how they were derived. Say you want to fit a line to some data. Your data is a bunch of (xi,yi) pairs. Through some kind of magic, the slope m and the y-intercept b are given by these formulas...

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...

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.E[SIZE="1"]r + R-\sumI =\sumV \sumI.E[SIZE="1"]r + 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...

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...