Questions tagged [fitting]
Questions on the use of Mathematica to construct models for approximating empirical data.
1,499
questions
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0answers
32 views
NMinimize with elimination returns strange results
I have a parameter vectors pars, par1, and a matrix data1 together with a vector result <...
0
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0answers
36 views
NonlinearModelFit gives weird result
I was trying to fit some data similar to sine, but always get weird results. So I searched and found this post.
Surprisingly, I can not reproduce the result. With below code
...
5
votes
1answer
171 views
A little complex data fitting in physics which my easy code can't solve properly
This is a data fitting in physics, however, some errors may estimate and cause failure.
First, I define:
...
0
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0answers
42 views
Fail to inverse the Piecewise function embedded in a NDSolveValue
I am trying to estimate a function consisting of a Piecewise function that included in a FEM solver.
I firstly developed my mesh for the FEM model based on @Tim Laska's work. The code is shown as
<...
3
votes
1answer
73 views
Precision Lost for Simultaneous NonLinearModelFit
I am having trouble with the below code. I have two data sets, dataf and datag, which are exponential decays. datag decays faster than dataf. These two data sets are then later joined to make datah. I ...
0
votes
1answer
32 views
Plot SinglePredictionBands associated with a FittedModel (e.g. LinearModelFit) that is supplied as a variable
I am puzzled about how to plot the SinglePredictionBands associated with a FittedModel (e.g. ...
0
votes
1answer
64 views
Nonlinear Model Fitting to Numerical Data with automatic elimination
I have an experimental data set {f,x,y,z} as
{{300., 2., 4., 6.}, {500., 0., 4., 25.}, {6600., 1., 15., 9.}, {100.,
5., 0., 2.}, {1100., 10., 8., 1.}, {1300., 7., 8., 18.}, {300.,
23., 5., 0.}, {400....
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0answers
51 views
Fit experimental data to find unknown parameter in system of ODE
I have a system of ode including 3 diff equation. I found two parameters Tcell and CD19 by experiment over time. Here is my dataset:
...
0
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0answers
51 views
Fitting the parameters of an SIR model
So I'd like to use Mathematica to fit the values of this SIR model. I don't know what function to use to find the best fit for S I and R by tuning b and k, the two parameters. I suppose I only really ...
0
votes
1answer
80 views
1
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2answers
102 views
Using transcendental equations with NonlinearModelFit
I'm trying to fit data($I$ vs $d$) to expressions like:$$
I(d) = \frac{0.013 d^2 \sin^2(\sqrt{1+\frac{0.013 d^2}{\Omega^2}} \Omega)}{1+\frac{0.013 d^2}{\Omega^2} \Omega^2},
$$
where, $\Omega$ is ...
6
votes
2answers
325 views
FindFit problem in "Debye temperature" fitting
I am fitting the Debye temperature using FindFit, here is my code:
...
1
vote
2answers
154 views
Any suggestions for improving my fitting?
This is not a completely Mathematica question, but I hope people who are familiar both with Mathematica and statistics could help me on this.
I have a set of data as
...
0
votes
1answer
87 views
Estimating parameters of a custom or constrained distribution
I am trying to estimate the parameters of a custom distribution (an approximation of the skew normal), but I can't get Mathematica to use DistributionFitTest, EstimatedDistribution, or ...
1
vote
0answers
53 views
Fixed-Effects Model in Mathematica
I need to fit a model with fixed effects (country and time) to adress the multivariate relation between a dependent variable for 22 countries over 8 years and two independents with the same dimensions....
1
vote
1answer
157 views
How to find appropriate surface fit?
I have 3d scan data (21 x 21 matrix), which is pretty rough, for which I need to find a smooth surface suitable for use outside Mathematica.
Here's my data:
...
1
vote
3answers
94 views
ComplexFit fits only part of fit parameters
I'm trying to fit experimental complex data with model:
model = s/(1-I*t*fr)
In the model I want to find real-valued parameters ...
1
vote
3answers
45 views
Problem with ParameterFitting:""The function value...is not a list of real numbers..."
I'm trying to use the data:
...
0
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0answers
67 views
How to fit an interference pattern with Interpolation and FindFit？
I have two sets of experimental data.
LightSourceSpectrum2.txt
InterferencePattern2.txt
The first one is the light source spectrum data, which can become a function of f[ν] using Interpolation. (Note ...
1
vote
1answer
109 views
Fitting data to a model
I am using the following code with the following data (which I called fn):
data (fn) here: https://pastebin.com/WwANBjNx
...
4
votes
4answers
564 views
Symbolic Regression
7+ years ago I posted a question here regarding symbolic regression in Mathematica. At that time there did not seem to be much built-in support for this. I'm interested in multi-input models of the ...
2
votes
0answers
64 views
How to perform feature selection for machine learning applications?
Feature selection is fairly easy in e.g. Python's scikit-learn which sports a module and tutorials or MATLAB.
Mathematica even touts that it uses feature selection ...
0
votes
0answers
27 views
General::munfl - Precision lost in LinearModelFit
I am new to mathematica so I am confused regarding the loss of precision in LinearModelFit. In building a linear model with uora (1 or 2) and encodeSeverity (1,2 or 3)
...
0
votes
2answers
92 views
How to find a fit for numerical data?
I would like to know how to fit a numerical data in two different ways. The first one is
...
8
votes
1answer
388 views
Improving fit by adding weights
I have the data:
data0 = {{0, 0.047}, {40, 0.071}, {80, 0.103}, {120, 0.169}, {160, 0.292}, {200, 0.498}, {240, 0.777}, {280, 1.000}, {320, 1.227}};
I want to fit ...
1
vote
1answer
132 views
0
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0answers
28 views
Logarithmic NonlinearFit with 10 parameters? Is Not a Real Number
I am trying to fit a collection of data with a fairly complicated function, and have been running into some errors. I am very new mathematica user, and am not really sure where I am going.
This is my ...
0
votes
1answer
84 views
Algorithm to switch from one to two gaussian fit
I have a big dataset that I have to fit with one or two gaussians. This dataset represents the evolution of a population in two different population as a function of time. That means that at same ...
1
vote
1answer
46 views
1
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2answers
59 views
PearsonChiSquareTest with experimental data including errors
I have a set of data in the form {x,y}, and the corresponding errors:
...
0
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0answers
46 views
Use Root object as a function in NonlinearModelFit or similar
I have a matrix and its eigenvalues are returned by Mathematica as a Root Object.
...
2
votes
2answers
66 views
Can't find parameter with findFit NMinimize
I have a data list and a function being to be fitted to the data to get parameters of the function as below. I can't find the parameters a, b, c, d with different below methods. Can you help me to ...
0
votes
0answers
75 views
How to find the appropriate fit?
Imagine we are given this set of data:
data = {{0, 1}, {1, 0}, {3, 2}, {5, 4}, {6, 4}, {7, 5}};
We fit the data with:
...
0
votes
1answer
69 views
0
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0answers
50 views
Plot the difference between data and fitting model
The following code defines fitting models (Chebyshev and Fourier cosine functions) from a data stored in a txt file.
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2
votes
3answers
188 views
Plot the error in the curve fitting
I would like to plot the fitted model and the original data punctually. For example, I have:
...
1
vote
1answer
47 views
Nominal variables in LinearModelFit must be specified before continuous variables
I am applying the LinearModelFit to a 90 x 5 matrix, in which the 4th variable is a nominal variable (i.e., x4 is a categorical ...
1
vote
0answers
41 views
fitting a dataset and choosing correct guess value
I am facing trouble in fitting some datasets with a model equation. Following is one of the data and code which I have tried:
...
3
votes
1answer
66 views
Even though the fit seems correct, NonlinearModelFit throws a failed convergence error
Consider the following data
...
1
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1answer
97 views
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0answers
16 views
Global fitting to a set of data while changing two variables
I have a set of thermodynamic data that I need to globally fit to a single equation. I currently have the data in a two column data where every 16 points is a new "set" of data points. I ...
0
votes
1answer
65 views
Suggest periodic fit for parametric data
I have some data that I'd like to find a periodic, continuous function that will approximately fit to:
...
2
votes
1answer
86 views
Fitting an equation to data
If I have the followind data:
data={{45, 2.93495}, {50, 2.94697}, {55, 1.9801}, {60,0.734437}, {65, -0.0128219}, {70, -0.695535}, {75,-1.35939}, {80,-1.47567}}
...
0
votes
3answers
84 views
Find order of polynomial approximation and LeastSquares for given datapoints
I have a set of data, where I'd like to find the order of the polynomial that approximates the data, and also know what the Least squares is.
My data:
...
4
votes
1answer
70 views
Binary (binomial) logistic regression with multiple independent variables: calculating the confidence range or prediction
Adding on top to this post here, I am looking for the confidence range (intreval) of the prediction of a multi variant binary logistic regression.
Can someone extend the solution in the post ...
1
vote
1answer
70 views
How to fit the following data?
Consider a dataset in the form {mN,tauN,x,value[mN,tauN,x]} (it may be downloaded here):
...
0
votes
1answer
54 views
How can I do NonlinearModelFit for only specific parameters?
I have a two dimensional data of the form $$\{x,y,f[x,y]\}$$. For example,
...
5
votes
0answers
298 views
Histogram (automatic binning)
There are different methods for choosing widths of bins for a histogram, like Freedman-Diaconis rule. In Mathematica, without choosing a specific method, with the command ...
6
votes
2answers
341 views
Fitting an exponential model: Mathematica vs. Excel [closed]
My data is:
data = {{0, 0.05}, {40, 0.079}, {80, 0.113}, {120, 0.18}, {160, 0.31}, {200, 0.5}, {240, 0.71}, {280,0.86}, {320, 1.02}};
With Excel we can fit the ...
2
votes
1answer
83 views
How to find the integrand by fitting data - spectrum reconstruction
Problem statement
I have some experimental data of measurement values vs. temperature.
Now, I want to find the spectrum which causes the measured temperature dependence.
The measurement values are the ...
