Fit Definition and 368 Threads

I am familiar with linear regression and the correlation coefficient. My current problem involves a data set that is pretty linear on a log-log plot. I have calculated the slope by taking logs of all my x's and y's, and doing the linear regression on the transformed data set. The resulting...

I would like to perform a complicated nonlinear fit with mathematica, which involves a numerical integral in the fitted model. But i can't get it to work. If I say something like: NonlinearRegress[data, NIntegrate[f[x, p1, p2, y], {y, 0, 1}], {p1, p2}, x] it says the integrand evaluated...

I want to start making my own LED lighting but need to find a small footprint, hopefully pre-made circuit that fits within a E27 Base Cap. I have just searched (almost) everywhere and have decided to just ASK. It needs to be about the size of the tip of a mans thumb to fit in the E27.

How do I fit the data given below into the standard form (ignore the part saying to use MathCad): http://screensnapr.com/u/apmqkd.png {{{0.002, 0.726}, {0.022, 0.739}, {0.042, 0.75}, {0.062, 0.759}, {0.082, 0.768}, {0.102, 0.776}, {0.121, 0.785}, {0.141, 0.794}, {0.161, 0.802}...

I have already turned this lab report in, but I am sure this will come up in the future. I just want to insure that I am doing it correctly. Homework Statement We did an experiment on the photoelectric effect. We found the negative voltage plateau and took readings of the photocurrent...

Homework Statement Suppose you have a quantity of water with a volume measurement of 1,535 +/- 10 ml. This quantity of water is to be transferred into a regular orthogonal container whose interior dimensions measure 15.0 +/- 0.1 cm long, 10.0 +/- 0.1 cm wide, and 10.0 +/- 0.1 cm deep. If you...

Shear stresses in shrink fit assembly? I'm trying to figure out what shear stresses there would be from a shrink fit assembly, if any. You have a cylindrical solid shaft and a cylindrical hub, where the shaft diameter is greater than the hub's hole diameter. The shaft cooled and thus shrunk and...

Does anyone remember a program (or know of something similar!) which, given a compilation of data, would search for equations which best fit the data? The one I'm thinking of came out ~ a year ago. It was a Windows-only program but it worked fine under wine. Unfortunately my time spent on...

Hi, I am applying to graduate schools this fall, and I could really use some guidance in finding a program that would be a good fit. The way I see it, there are two things I must consider: Applying to programs that may accept me, and applying to programs I would want to attend. :) I attended...

I am looking for math software that will fit a set of points with a cubic spline (or other technique)...then allow the user to change the shape of the curve by dragging it...and continuously fit the curve as the dragging is occurring (or fit the curve after the dragging has stopped). The point...

I have a project I am doing for a professor and unfortunately I cannot get ahold of him to help me out, so I figured I'd ask you guys. Of course, I tried to ask The Google about this first and didn't get anywhere. Here is what I am trying to do: The part I am having trouble with is using SVD...

Describing the "goodness of fit" of a model Hi there, I would like to ask advice on an appropriate way to define how well a measurement 'matches up' to the predicted response. In other words, I have a set of data for bandwidth measurement for an LED (amplitude vs. frequency). I also have a...

I just completed my undergrad in physics and applied math, but I liked the applied math more partly because the physics got too abstract for me - I liked classical mechanics more than quantum mechanics. As a result, I had been strongly considering getting my MS or phD in mechanical/aerospace...

Hey folks, Am I doing something wrong here? It just seems like I should be able to get a better fit. The data is plotted for the H2-->2H reaction data. I have attached the .xls file. Don't worry, no macros :wink: I created it on a Mac, but hopefully everything converts correctly...

Homework Statement Given a series of measured data points (>1000) x,y find the best fit parabolic curve where the constant A (below) is given. Homework Equations General 2nd deg equation describes conic sections: Ax2+Bxy+Cy2+Dx+Ey+F=0 for a parabola B^2=4AC, AND in this case B<>0...

I always hear that the "global fit" EW precision test. It seems that I understand it a little. But I am still very clear. Who can shed light on it?

Homework Statement Fit P(w) to determine Q, and w_0, and R. You should put in Vrms as a known constant. Homework Equations P(\omega)={\frac{V_{rms}^{2}}{R(1+Q^2(\frac{\omega}{\omega_0}-\frac{\omega_0}{\omega})^2)} Q=\frac{\omega_0}{\Delta\omega} R=R_load+r The Attempt at a...

Hey Guys, I'm a finance guy, who's developed a fascination with physics in recent years and read quite a few of the books available to non-scientist readers who want to understand this stuff. Here's my situation: - I understand Newton's gravity, in broad terms. - I understand GR in broad...

I think this command exists, but I can't remember what it is. Suppose I have a document that takes up maybe three and a half pages formatted normally, and I want LaTex to fit it into exactly three pages. I could just tweak the margins, line spacing, font size, etc. myself, but I'm fairly...

I understand that Johns Hopkins is a pre-med school. But, if I'm interested in genetic engineering, is that a good school to apply to?

I have some measurements from a physics lab experiment and I am coding in Matlab a fit for the data. [Note this is not a problem with Matlab, my problem here is theory] In normal regression of statistics the RMSE is given by: s=\frac{\sigma}{\sqrt{n}} =\sqrt{\frac{\Sigma (\epsilon...

Hey all, I have a bunch of data that varies over many magnitudes. I was hoping to use log bins to capture the short and long term features of the data. My question is, how do I bin the data, and how do I assign appropriate errors so that I can fit the data to some theory (maybe a power law)...

Here's my data: data = {{0.0, 2.91}, {0.25, 2.96}, {0.4, 3.08}, {0.7, 3.18}, {1.0, 3.25}, {1.2, 3.31}, {1.4, 3.37}, {1.6, 3.45}, {1.8, 3.49}, {2.0, 3.54}, {2.5, 3.65}, {3.0, 3.74}, {3.5, 3.81}, {4.0, 3.88}, {4.5, 3.94}, {5.0, 4.0}, {5.5, 4.04}, {6.0, 4.09}, {7.0, 4.19}...

In regards to dark energy or dark matter... Why does the science community create new science to fit the math rather than fix the math to fit the science? Are we so confident in the math that we have to adjust the science to match? Why are we so confident in the math? If galaxies rotate...

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...

Hello, I am trying to write an algorithm to calculate the Least Squares Fit Line of a 3D data set. After doing some research and using Google, I came across this document, http://www.udel.edu/HNES/HESC427/Sphere%20Fitting/LeastSquares.pdf (section 2 in page 8) that explains the algorithm for...

Hello, I am trying to write an algorithm to calculate the Least Squares Fit Line of a 3D data set. After doing some research and using Google, I came across this document, http://www.udel.edu/HNES/HESC427/Sphere%20Fitting/LeastSquares.pdf (section 2 in page 8) that explains the algorithm for...

I did a least squares fit project for physics and now i have to say the value of G and the slope. I know that slope is m from the equation y = mx+b but how do i determine G?

I was wondering if someone could explain how to compute the Least squares fit to a straight line

I was wondering if someone could explain how to compute the Least squares fit to a straight line

1) Linear fit I am running an experiment to find the linear relation between displacement (X) and voltage reading (V) of the measurement, when fitting a linear line to my measured data, such that: V= m*X + b; Based on the following links...

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 =...

I have a set of data that consists of about ~1000 data points, each of which has two measurements. I have a series of models with two parameters that I have fit to this data to find the best fitting pair of parameters. There is quite a spread around the best-fitting model, because none of the...

Can anyone help me with this? The basic equation in quantum mechanics says that E=n*h*v(nu) where n = 1,2,3,... How is then possible that the quantum linear harmonic oscillator has an energy E=(n+1/2)h*v? If someone can explain this, please help

Homework Statement For the following data, find the least squares fit of the given form x=1,2,3,4,6 y=14,10,8,6,5 h(x)=ae^x+be^(-x) Homework Equations The Attempt at a Solution So I tried to linearize the equation by taking the natural log of everything...

I need to fit a tail-heavy "Gaussian" curve Hi, it's been a long time since I've been around PF. Homework Statement This isn't a homework problem per se, but I've been trying to fit some scattering data using a Gaussian function using a least squares approach and it's not working so...

Hello all, I am trying to fit a surface to a 1920x1080 grid of evenly spaced data points. The values are supposed to be more or less uniform (its an image of a uniform white light source). So I would like to fit a plane to it (but maybe a paraboloid if it is not quiete uniform). What method...

Hi, I am having some 2d and 3d data files (from some nmr experiment, as a matter of fact) and the data plot for that is such that most of the points are coming together now I want to draw ellipse around 2d data point and ellipsoid around 3d data point with the condition that 90% (or any...

We are using the MatPIV Matlab toolkit: http://www.math.uio.no/~jks/matpiv/ However, we are having trouble using the toolkit with viscoplastic media. It was expected to find a yielded region and a unyielded region, however, from the results of MatPIV it appeared that the whole area was...

Will my Corsair TX750 fit in a Coolermaster HAF 932 full tower gaming case?

I have three different parts: 1. An Aluminum Bronze Outer Ring 2. A Neoprene Ring 3. A Phenolic Composite Ring. The (2) fits into a recess in (1), (2's) purpose is to seal between (1) & (3). What I would like to do is create a calculator on excel that will calculate the force required...

You can get a calculator and start counting the errors and false assumptions contained below if you want.. but I got to ask.. If the furthest we can see is 14 billion light-years away (because it's been 14 billion years since the big bang and that's all the time light has had to travel such a...

So, I have a table of data, and I'm trying to get a curve to fit the points. I haven't tried excel yet, but I have tried these things: 1) Openoffice.org 2) Gnumeric 3) XMGrace - Gnumeric was straight-forward, but lacked many abilities. - Openoffice.org couldn't fit the curve well enough...

Hi, I'm a new member who has just embarked on my journey into Quantum Mechanics and String Theory. I was a grade A student in contemporary high school physics, however i am aware that i have a lot to catch up on (i assure you the textbooks are on order), so please don't attack me if the answer...

Homework Statement i need to find the mass of a new found planet at a given radius from the sun (R) and with a given cycle length (T) Homework Equations Kepler and Newton The Attempt at a Solution of course if R and T would fit with keplers third law then there would be no way to...

The universe is around 13.5 to 14 billion years old. That means that if everything started from one singularity which was the big bang, and nothing can travel faster than the speed of light, the size of the universe must be at most 14 billion light years in size. But even that is an extremely...

Hi gurus, I was hoping you guys can help me with a little something: I have just purchased a 12V DC motor with a shaft diameter of 5.4mm (Oddly enough, the description on the ebay page says 5.5mm, but the technical drawing attached, says that its 5.4mm). In any case - i am looking for...

Hi, does anyone know how many squares of side 1 millimeter can fit in a big square of side 1000.25 millimeters ? Cheers, Aaardvark.

I have a bunch of data x1, x2, x3, ... x49, z. I need a function f(x1, x2,... x49)=z. Does anyone have suggestions for a method that they have used before or key words to google?

Well, it is confusing the meaning of the quote, "If the facts don't fit the theory, change the facts" by Albert Einstein. Anyone knows the exact meaning of it? :smile: