Fit Definition and 347 Threads

Hello everyone, A question about curve fitting. Hope you can share some helpful hints. Given some data we plot a graph y versus x. How do we approach the problem from a curve fitting standpoint? For example, using Excel, if the data "looks" linear from the graph, we choose a linear fit and...

In another thread I posted this graphic, How does this picture above need to be modified to include gravitation if possible? What does the M+ and the M- represent? Is there a place for the Higgs particle in the above picture? Could the above picture be turned into a movie and show say an...

The problem is the following : I have some measured data's obtained when measuring a physical process. Let's call these : yE,L where E and L are 2 physical parameters of the experiment (an energy and a length). I also know that : $$\frac{y_{E,L}}{\sum_{k=1} ^{k=100} {\epsilon_{E,L} (k * v) *...

Hi All, I am trying to wrap my brain around Latent Class Analysis (LCA). In the mean time, does anyone know how to test for goodness of fit and whether a given number of classes is somehow optimal? AFAIK, Log-Likelihood should decrease as a measure of improved fit when adding latent classes...

I have attached an image showing a (what I believe to be) simple problem involving arranging four blocks, each of different dimensions. Yes, the blocks fit together perfectly in the first arrangement shown in the diagram when there are no gaps. I'm convinced that the solution is likely easily...

I've come across a problem with my least squares fits and I think someone else must have analyzed this, but I don't know where to find it. I have a converged least squares fit of my spectroscopic data. Unfortunately, the physical model, on which the fit is based, is mediocre. The deviations...

I have five data points (x,y,z), with two independent variables (x,y), and have written a function in a separate file z = f(x,y,A,B,C), with three undetermined constants (A,B,C). How can I use a Matlab fitting program to try and determine the constants? I've written a fit function before where...

In string theory, particles is vibrating strings. However, QFT treats particles as excitations in a quantum field. Can both of these theories be correct? If so, how does them fit together?

Hi. Suppose I have a function y=f(a,b;p;x) where a, b are known with some uncertainty and x, y were measured multiple times. I want to find p through best fit. I consider a, b to be gaussian variable. I can imagine multiple ways to do this: * I consider a, b parameters like p. I don't like...

Homework Statement An article in Business Week reports profits and losses of firms by industry. A random sample of 100 firms is selected, and for each firm in the sample, we record whether the company made money or lost money, and whether or not the firm is a service company. The data are...

I have some data and I need power fit.And display it on the graph.But I couldn't find the right codes for it.(I need codes) Here my graph, Here my codes, >> x=BN(:,2); >> B=BN(:,1); >> plot(x,B,'go') >> plot(x,B,'go') >> hold on >> xlabel('Distance (m)','Fontsize',21); >> ylabel('Magnetic...

I have a lineer data and I want to write the equation of it on the graph. The x-axis is inverse distance (1/m) and I showed as "d" The y-axis is capacitance (C) and I showed it like "C" My data name is d_C Here my codes that I used for now >> d=d_C(:,1); >> C=d_C(:,2); >> plot(d,C,'go'); >>...

The problem statement, all variables and given/known data with attempts While solving problems of Goodness of fit, I'm faced with an issue, how to decide which ratio to consider to find the test statistic from given set of observations. E.g. 1 A supplied sample contains four types of seeds and...

I wanted to see if someone could tell me if I would fit well into a field in physics. I feel like it would be an amazing experience in college and is something I could really do for the rest of my life. The only thing is I don't know if I have the intelligence to make it happen, or the work...

Currently I am generating an ID from an image by using K-Means to separate brightness levels into 8 levels (clusters) and order them brightest to darkest. For each cluster I calculate: 1) Their center points as a percentage of image size (using average pixel coordinates) 2) Average distance of...

Homework Statement I have the following data which I would like to model using an exponential function of the form y = A + Becx. Using wolfram mathematica, solving for these coefficients was computed easily using the findfit function. I was tasked however to implement this using java and have...

I'm trying to make two metal cylinders which will overlap to act as a valve for the outer cylinder to rotate around the other. I need to be able to stop water from the reservoir around the outer cylinder from leaking down between the plates and into the gap for the gear which will give the...

Given that 1.34Tbit of information can fit on a square inch of average hard drive surface, how many 400 KB files could be written on a square millimeter? I did the math and came up with about 634. This seems unbelievably high and I wonder if someone would have time to check it. I kind of need...

I'm a Physics undergraduate at University and in my labs module I had to recreate the Rutherford Scattering experiment. The basic setup was similar to this: My problem is that this setup only records data in one plane and not 3D. In reality the particles are scattered in a sort of cone...

In one of my problems, I have this set of data. I have to create two best fit lines, and find a value of absolute zero for both. The first best fit line is to be made assuming there is NO uncertainty in P. This is rather straightforward, just use the normal linear regression, find a slope...

AFAIK antimatter was produced equality in the big bang, and in the matter antimatter fight the matter won . Does antimatter react to gravity the same as matter, surly if it does then the antimatter will be annihilated due to matter antimatter mixing IF matter repels antimatter how did the...

We have two theories namely,Quantum Field Theory which works very well at sub-atomic scales, and the General Relativity which works very well at very large scales.So, my question is where does statistical physics/mechanics fit in? What role statistical physics/mechanics play in today's modern...

Hi, I am new to this forum. I need to design an interference fit for a 1.5 mm thick SS ring. The interference fit is between this ring and another 1.5 mm thick SS sheet metal can without any groove. The ring is bent outwards at a specific angle.(please refer attached image) We know amount of...

the second law of thermodynamic state that their will be more chaos, and natural selection in the opposite of that. maybe this is a stupid question but can somebody anser this

While using a piece of jewelry ie a fine chain hanging against a piece of graph paper then placing an origin, axes and scale on the paper I collected the position of the chain as a set of coordinates (x,y). Entering the data into curve fitting software a perfect fit for a polynomial degree 2...

Sorry if this is more of a HW question (if so then moderator please move my question. Thanks!) Hi, I'm trying to get an expression for a best fit curve of the combination formula (##_nC_r##). As far as I can tell, the curve is a simple parabolic curve, and its shape doesn't change. It's just...

Homework Statement Hi, we investigated how the length of a pendulum affects the time period of oscillation. We collected data by changing the length (l) of the pendulum and measuring the time period (T). We then squared the T value before plotting it on the y-axis and on the x-axis we just...

Hi All, I ran a binary logistic of Y on three different numerical variables A,B,C respectively. I am having an issue of separation of variables with all of them, meaning that there are values Ao,Bo, Co for each of A,B,C (different values for each, of course) so that for ## A>Ao, B>Bo...

Homework Statement [/B] (a) Calculate the load current using Thevenin's Theorem (b) Calculate the load current using Superposition Homework Equations N/A The Attempt at a Solution There have already been a couple of historical posts of this question but those threads don't give me any...

I am working in ℂ3 in this question. (If it will make it easier, we can work in a bounded subspace.) Suppose you have, in each of the three complex planes whose Cartesian product make up the space in question, a set of points. (You do not have knowledge of generators of these sets, or whether...

Hello everyone help please I need to fit experimental data with a theoretical model using the MATLAB software what is the best way to do it? thx for advance

Hi, I have a simple/fast question... Can you reliably use a Poisson function to fit on data that seem to be Gaussian distributed (although that is due to the large number of the mean)?

As a part of an experiment in radioactivity, we placed an alpha particles emitting source (Am) and a sensor in a vacuum chamber, and measured the power (number of particles per time unit) for various angles of the sensor. Our goal is to fit a theoretical function to our measurements (power vs...

The ancient Great Pyramid of Giza had a base of 230.4 meters, and a height of 146.5 meters. A ping pong ball has a diameter of 40 millimeters. The volume of the Great Pyramid = (b^2 x h)/3 = (230.4^2 x 146.5)/3 = 2,592,276 cubic meters. The diameter of a ping pong ball is 40 millimeters =...

I've been getting this as almost a robotic response from every company I've applied to lately. "Unfortunately, You are not the right fit at this time, and we are considering other candidates...blah blah." I'm starting to think it's because my experience isn't specialized enough? I have an MS...

Hi! I have to fit a blackbody spectrum to some data points. The y-axis is in mJy and the x-axis is in log_10(freq). My code looks like this: from __future__ import division import matplotlib.pyplot as plt import numpy as np from scipy.optimize import curve_fit h = 6.63*10**(-34) c =...

Hello. I am looking to amplify a sinusoidal signal generated from an AD9850 DDS. It appears the output is 1Vpp @ 27.12MHz when connected through a 50ohm cable to an oscilloscope. I need the total power output to be 5watts after amplification with a very clean sinusoid. The output will be...

Homework Statement Hello, I am using CasaXPS to model synthetic peak models for X-ray photoelectron spectroscopy data. I am fitting. The software has a lot of manuals online but they do not explain how they yield a Residual Standard Deviation, after each fit iteration. Most software use...

Hi All, I am having trouble seeing how Relational Databases (RDBS) can be used in the world of big data. The inflow of data seems to be way too fast for the database to reflect what is going on at a given moment. I understand this issue is supposed to be addressed by data warehouses. Is...

Hi! I am trying to build a better understanding of quadratic functions. So I had this idea of trying to fit a quadratic function to two arbitrary points, but I am not sure how this really works. Given the points (-4,1) and (12,1) on a Cartesian plane, how can a quadratic function be defined...

Hello, I am currently a sophomore double majoring in Physics and Math at Purdue University. I have a 4.0 overall GPA and would love to earn a Ph.D. and probably a postdoc position in the future. But what should I concentrate in? To which graduate program should I set my eyes on? Here are...

I have some data and in said data I had 2 peaks, to which I fitted 2 Lorentz functions. The sum of these 2 functions gives me a 3rd function. Now, I need to find the integrated area of the 3rd function. Originlab gives me the area of the 2 fits, but not of the 3rd function. Summing the area of...

Hi Everyone I am Arman.I am at first grade in Physics and I have trouble to understand Matlab.Now we did Energy Conservation Experiment.I draw x-t and F-t graphs using matlab.Instructor told us we should use spline fit to draw a F-t graph.I don't have a toolbox about it.She told us some code...

Hi guys! I am trying to fit a function whose x data depends nonlinearly on the parameter of the fit and I am having hard time doing that! I will explain better: from my experiment I was able to measure my ydata e my x0 array and I know that my xdata are: x=x0+a/(1+4x^2), with a being a...

I am wondering which kind of job will suit me the best. I have studied mechanical engineering and love to do the theoretical exercises. I enjoy exercises concerning fluid dynamics, thermodynamics, mechanics, calculus, and so on. I can easily do the theoretical exercises the entire day without...

a car goes around a vertical circle; determine the period of one cycle if the radius= 6m mass=800kg, gravity=9.8m/s^2 gforce = 6g my attempt at the bottom of circle: fnet=ma fn+fg=(mv^2)/r fn+fg=(4∏^2mr)/t^2 t=√4∏^2mr/fn+fg t=√4∏^2(800)(6)/(fg+fg) <-----value of fn and fg will be in opposite...

Hello, I didn't know where to put my question, but I think here is the best section for it. http://im60.gulfup.com/apkrpJ.png The problem isn't that I can't solve it, I actually did but I don't understand the concept ! -- I don't remember anything from my high school stat and I didn't do...

Suppose I want to find a model for a background from the data of it... One way is to try different fittings and compare the values of their ##\chi^2/NDF## if they're close to 1 or not. However what happens when two fits are really close to one? For example if I take a ##M_{\gamma \gamma}##...

Homework Statement Homework Equations I think it will make use of tables... The Attempt at a Solution Can someone tell me the solution step by step of this problem? Help me please :( Thanks in advance..

Hello everyone. The physics forum is a great online community, and I used to spend a lot of time browsing the philosophy pages. But now I've had to register and post, because I've got a very specific problem with regards mechanical engineering. My problem is relating to torque transmission...