Fitting Definition and 242 Threads

I am trying to fit a cosine function to two points knowing that the first is an inflection point (e.g. a trough) and also knowing the gradient at the second. I have a gut feeling this has a unique solution it just needs the right identities and massaging but as of yet I haven't found the way...

I have a set of data points \{\{x_1, y_1\}, \{x_2, y_2\} ... \} each with an uncertainty \{\{dx_1, dy_1,\}, \{dx_2, dy_2\} ...\}. Is there any way of fitting a nonlinear model to the data that incorporates the uncertainties on both x and y? I know that you can use the Weights command to...

Hello everybody, So for this wind monitoring project I'm getting data from a couple of 3d sonic anemometers, specifically 2 R.M.Young 81000. The data output is made digitally with a sampling frequency of 10Hz for periods of 10min. After all the pre-processing (coordinate rotation, trend...

Can you fit data that is imported into Mathematica 8? I am just using the Import command, and I cannot figure out how to work with this data. I would really like to fit my curve. This is the code I used to import the data: Import[datafile.xlsx"]

I am trying to use Mathematica to fit a curve to these data points ListPlot[{{2*Pi/(1 - 0^2/16), 5 (3 - Log[2])}, {2*Pi/(1 - .05^2/16), 10 (3 - Log[2])}, {2*Pi/(1 - .1^2/16), 15 (3 - Log[2])}, {2*Pi/(1 - .15^2/16), 20 (3 - Log[2])}, {2*Pi/(1 - .2^2/16), 25 (3 - Log[2])}...

I am wondering if there is any way to create a model that can be used in a RANSAC method where a spline could be determined from a noisy 3d point cloud. What i have is a volume containing a set of points in each xy-plane, having say 400 of these in the z direction and a spline shape emerges...

1. Homework Statement Determine the dispersion (dn/d lambda) at a wavelength of 800 nm from fitting equation. 2. Homework Equations Fitting equation from graph of n vs 1/lambda^2 y = 7e-15 x + 1.60 3. The Attempt at a Solution Since it is a plot of n vs 1/lambda^2 I...

Homework Statement Determine the dispersion (dn/d lambda) at a wavelength of 800 nm from fitting equation. Homework Equations Fitting equation from graph of n vs 1/lambda^2 y = 7e-15 x + 1.60 The Attempt at a Solution Since it is a plot of n vs 1/lambda^2 I thought that...

Long story short I want to Mount a Computer inside an Antique typewriter maintaining the look and feel of the antique. My initial plan is to dissasemble a Toshiba Satellite and disgard any thing I don't need (plastic housing, Maybe the speakers, and any chassis' I can do without) I have so far...

Hello, Let me get right to my problem. I have an experimental distribution and a single-parameter theoretical distribution. I want to find the value for the best fit theoretical distribution that agrees with my experimental data for the bulk of the distributions (the tails of my...

never mind i figured it out.

Fitting points to "skewed" sinusoids Hello, I have a problem related to least square fit of data. Let me start from a step back. I have a set of points, given as x-y coordinates. x represents an angle and y the corresponding value of a function. I am fitting sinusoids to those data points...

Let's say I have a series of 100 coin tosses, heads or tails. In fact (for my actual data) I don't know if subsequent trials are correlated or what the actual probabilities of getting heads or tails are. Nevertheless, I want to fit a geometric distribution, which gives me the distribution of the...

Hi I have the following piece of code: dataX = -4:1:4; dataY = [0 -1 -10 -40 -55 10 40 10 1]; figure(1) plot(dataX, dataY, '*'); x = -2:0.01:2; plot(-4:0.01:4, 1*conv(exp(-x).*heaviside(x),sin(x)), dataX, dataY, '*') mdl = @(a, x)(a(1)*conv(exp(-x).*heaviside(x),sin(x)))...

If I have a set of n numbers, (n=0,1,2, ... n-1), what is the maximum number coefficients in a series I would need in order to find y=f(n) true on the integers up to n-1? Or is that something I just have to check after fitting it? ( does it need an nth degree polynomial?) Another question...

Hi, I have a dataset of a random variable whose probability density function can be fitted/modelled as a sum of N probability density functions of normal distributions: F_X(x) = p(\mu_1,\sigma_1^2)+p(\mu_2,\sigma_2^2)+\ldots+p({\mu}_x,\sigma_x^2) I am interested in a fitting method can...

Dear all I am trying to fit a simple ARCH(1)/GARCH(1,1) model to a set of binary data, i.e. I assume a latent GARCH process that is only observed at the values a and b, say (whenever it crosses or hits those thresholds). I found some ideas on fitting a censored GARCH (by SX Wei, for example...

I thought of a problem a few days ago and I have no idea as to its solution. I posted this on Reddit and xkcd forums earlier but not much has been solved apart from the area of one circle. Suppose you have a boundary formed by the curve y=e^(-x), and the lines x=0 and y=0. In this boundary you...

Say I have a function: f(x,y) I have values for f and y such that I can make a plot of f vs y... however, from the values of f and y, I am interested in finding what x is. The x value should be a constant that is optimized to fit the f vs y graph. Is there a way I can do this in...

Good day, I am relatively new to mathematica, and I am using it to fit a formula to a dataset that I have. To begin with, I am having issues with a very simple part, namely with a ListPlot. I have an xls file with 2 columns and 26 rows, corresponding to an x and a y value. Using import, I...

Hi, I am trying to fit sample data to a Johnson SU distribution in S-Plus. It seems not many people use S-Plus, so if you are familiar with R then you could help as well. The code that I have is: f.Jsu.fun.takeslist(x,g,l,r,e) which is a function I have made that calculates the PDF of...

I have 100 data points that I want to fit in Excel I can do this with NORMDIST no problem but I'm also trying to do it without it to no avail! I'v tried plotting the data using the Gauss function: y(x) = \frac{1}{\sqrt{\pi \sigma^{2}}}e^{\frac{-(x - x_{0})^2}{2\sigma^{2}}} where x is a data...

I have a GPS track I'd like to plop on top of a map. The region of the track is very small, no bigger than the area of a city. I also have a bunch of shape files to build up a map of the city with all the buildings, roads, etc. in separate shp files. Although the shape files actually contain...

Homework Statement This is not homework, just a personal project. I do not know if this is the correct section to post, sorry if it's not. I'm using a motion analysis software to track the position of a bouncing ball (y vs t). I imported the data into Excel and the graph is attached. What type...

Homework Statement Im trying to construct a function in MATLAB that models linear least squares model fitting through the use of normal equations. Homework Equations Normal equation (A'*A*c)=(A'*y) A= [column vector of all x ; column vector of all 1] y= [column vector of all y] c = [b;a]...

I have two matrices, A and D, with same numbers of rows and different numbers of columns (A has many more columns than D), I want to find x and y such that ||Ax-Dy||_2 is minimized. I.e., I want to find the closest vectors in span{A} and span{D}. Seems like a simple problem, but couldn't figure...

I have some data to calculate the photoelectric effect, and with my measurements I have made a graph using the least square fitting for voltage vs. frequencies. If I have an error of x for all voltages (V) and y for all frequencies f. How do I calculate the error of the values m and a if my...

say we have data set {y(t sub i), t sub i} Where i=1 2 3...m. I know how to fit these into a line of the form ax+b, but how about fitting into a constant??

Hi folks, I am currently working on a project involving an unknown crystal sample. I have now identified the sample but I would like to quantify my findings by considering how well the structure I have determined fits other known structures. I have already ruled out fitting atomic positions...

Homework Statement I need to fit a model to some data, where y = systolic blood pressure and x = time in weeks. The problem is, all of the 'usua' trendline options on Excel produce awful R squared values. Is there some other method I can do to fit a different sort of model that would be...

Cannot seem to find such a connection. The UHV vacuum sits around 1x10-8. The fitting needs to be rated for cryo temps. Thanks

Hi, I'd like to fit a straight line to some data which is noisey with gaussian noise with some st dev. Using least squares, I can estimate the slope and intercept. I'd like to know the uncertainty in these numbers. I can find the residue, I believe this is a measure of the variance of the...

Homework Statement I was wondering if there was a general method for finding a function that fits a set of data for a damped harmonic oscillator I'm currently writing up a presentation on the experiment for the gravitational constant and the way i did the experiment was to use a torsion...

Homework Statement Inverse Laplacetransform (3s+7)/(s^2+2s-2) Homework Equations (3s+7)/(s^2+2s-2) The Attempt at a Solution Split into 3s/(s^2+2s-2) and 7/(s^2+2s-2). I can't find a fitting transformpair(I use tables/formulas).

Hi I am stucked on a problem of distribution fitting. I have collected data about bus arrivals on field in a week time and now I want to fit a statistical distribution to these data. I know that theoretically should be Poisson or smthg but to make a correct step by step observation I need to...

Hello, I have the following points that need to be fitted with a curve: (1,20);(2,4);(5,3) I'm wondering how to use the http://en.wikipedia.org/wiki/Lagrange_polynomial to do this. If possible, can these points be fitted with a cubic function? I tried to fit a cubic to this, but...

For example, suppose you have some data where each point takes its value from U(0,1) with probability p and the Cantor distribution with probability (1-p) where p is fixed but unknown. Here the standard MLE approach falls over, so how would you go about estimating p?

Hi all, I want to fit a curve through 6 points (please see figure attached, the curve in the picture is a drawn one not a fitted one. That is just to give a feel how the fitted curve would look like.) in a log-linear plot. Is there any way I can do it? Thanks.

Im analyzing some data from a previous student I am trying to plot a line of best fit over the histogram and hense find the value of the coefficiants the files had to be loaded as -ascii so this is the code i have typed so far x=load('filename.mat','-ascii'); mean(x); hist(x,300) this...

Professor forgive me it has been many years since my last physics problem, but I was looking at the pressure gauge mounted in a T fitting on our shop compressed air line, and how the reading dropped when various high cfm tools were in use. As I understand it the indicated pressure reflects two...

i have a piping system and i know the initial flow rate into the system. the the piping system steps down several times through tee fittings on its way to a final nozzle in which i have required minimum flow rate. i know the flow rate going into the tee but i can't find any information about the...

Homework Statement I did this one before a few weeks ago but now I can't seem to get the right answer: An elliptical disk is to fit snuggly and squarely into a notch cut into a rectangular plate. The notch is 180 mm wide. If the disk's major axis is 280 mm long and is parallel to the long...

I have a piecewise function described by g_1(x) as shown in the figure below. I wish to make a smooth curve, g_2(x), to fit (but not necessarily exactly) g_1(x). The only conditions are: Both curves must start at (0,0) and end at (a,0). The area of both curves must be the same. How do...

In the ASHRAE fitting database, there are negative duct fitting coefficients. I assume this means that that particular fitting will produce a pressure regain. However, I am unsure that it would be a static regain because: the formula is P(total)=C*P(velocity), and P(total) only can only drop...

Hi- I apologize if this has been covered elsewhere, but after much searching with no luck... I am taking a lab class, the first in a while, and am using Matlab's Curve Fitting tool to fit data to exponential curves. My question is how to translate (if possible) the "goodness of fit"...

Homework Statement Suppose that you are given a set of observations (tk,yk), k = 1,...,M. You plot these points on a sheet & it seems that the relationship between (t,y) could be approximated with a second order polynomial. a) Write down the model in the form y = Ax + c. Specify the vectors...

Hi, what are some good textbooks dedicated to this subject? I have a short time to learn everything about this subject (upto a certain level). I'm trying to fit a non-analytic curve (whose form I know) to some data. edit- sorry, I don't only mean non-linear, I mean non-analytic. The curve is...

Hey, I have a graph for which I am supposed to fit two linear least squares line and minimize the combined residuals (the lines intersect)... I would really appreciate some info about how to do this or what this type of data analysis is called so i can google the step-by-step method. Thanks!

Hey, Not sure if this is the right section to post this but ... I have a graph for which I am supposed to fit two linear least squares line and minimize the combined residuals (the lines intersect)... I would really appreciate some info about how to do this or what this type of data analysis...

Homework Statement I'm trying to go about fitting some (x,y,z) coordinate data that I got out of a simulation to a parabola, but I'm not entirely sure how. Is there a general equation for a parabola that instead of having usual (x,y) coordinates has (x,y,z) coordinates? Homework Equations...