All Questions
Tagged with linearmodelfit or fitting
1,768 questions
0
votes
1
answer
201
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Interpret P-value in ANOVA table and Parameter Table
I wonder how different between P-value in these 2 tables since they are not equal. I have check on Mathematica document. There is no information about these 2 tables in comparison.
- 25
0
votes
1
answer
98
views
Problem with NMinimize and NonlinearModelFit
I have data points of some experiment and system of ODE, that approximate this data.
...
0
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0
answers
62
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NonLinearModelFit Usage Help
I am using FindFit to fit a piecewise linear interpolant (vs. x) to data (vs. t) using a convolution. The FindFit portion of my notebook is attached below. The fit appears to be reasonable despite ...
- 1
2
votes
3
answers
403
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Calculating derivative of experimental data (with noise) using tangent method
I have some experimental data and I need to do a derivative. I looked at various answers how to approach that at e.g. here. But I am not happy with them (the curve is not smooth as needed plus the ...
- 4,036
6
votes
2
answers
256
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Parametric curves from 2D data using DFT
There is a very cool application in maple for generating parametric Curves from 2-D Data using Discrete Fourier Transforms https://www.maplesoft.com/Applications/Detail.aspx?id=154546
I wonder if a ...
- 373
4
votes
2
answers
495
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Evaluating an integral symbolically seems impossible
I have an integral of general form
$$ i_n(z)=\dfrac{z^2}{K_2(z)}\int_1^{\infty} \dfrac{\left(x^2-1\right)^{n+\frac{3}{2}}}{x^{2n+1}} \exp(-zx) dx $$
$K_2(z)$ is the bessel function and $0.01 \...
- 878
2
votes
2
answers
107
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Insufficient memory in Nonlinear Model Fit with ParametricNDSolve
I try to fit parameters to ODE solver with chemical kinetic eqations:
...
- 534
-1
votes
3
answers
101
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Interpolation of a function from numerical data and getting plots [closed]
I need to plot between two functions $f(h)$ and $g(h)$. I have the numerical data of $f$ w.r.t. $h$. So I just tried to get the expression of the function using the codes f[x_]=Fit[data,{1,x,x^2},x] ...
0
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1
answer
198
views
0
votes
0
answers
70
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Parameter distribution from NonlinearModelFit result
Is it possible to construct a parameter distribution (e.g. Normal or StudentT) from the Estimate and Standard Error of a NonlinearModelFit result? The SE is the square root of the variance but what is ...
- 11
4
votes
1
answer
189
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MeanPredictionBands not working in ResourceFunction["MultiNonlinearModelFit"]
I have a problem creating MeanPredictionBands for a FittedModel from the ...
- 121
2
votes
1
answer
190
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How to properly fit experimental data to a nonlinear model?
So I'm trying to fit experimental data to a nonlinear model using the NonLinearModelFit command, but it isn't quite working.
The plotted data set looks like this:
The data is to be fitted with
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3
votes
1
answer
220
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How can one find the corresponding black body temperature, when trying to fit the integrated planck function (energy flux) to a value
Given a certain numerical value for the energy density flux $F$ of a star, e.g. the solar constant $s_\odot = 1362~\frac{W}{m^2}$, and a certain wavelength range corresponding to the irradiated energy ...
- 141
1
vote
1
answer
91
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Implementing a way of generating binary data for use in a logistic regression
Background
I want to generate a set of test data to be used in a logisitic regression.
As an example consider the scenario where a cannonball is fired at a wall. There are only two outcomes: the wall ...
- 317
1
vote
1
answer
144
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Problems with FindFit-function
this it's my first question in this forum, so first hello! I have a problem with one of two datasets. With the first is everything fine and it works the way i imagined it would. With the second ...
- 11
5
votes
1
answer
190
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Logistic regression - Confidence interval for x axis
Background
I have a set of binary test data of the form
...
- 317
0
votes
0
answers
72
views
NonlinearModel Fit Help?
I'm trying to fit some data to a nonlinear model, but I'm getting the following error:
NonlinearModelFit:: Failed to converge to the requested accuracy or precision within 1000 iterations.
This is my ...
- 1
1
vote
2
answers
433
views
Mathematica "FindFit" starting value
I believe I have encountered a case in Mathematica where the FindFit function is not able to capture the fitting parameter value even when the starting value is approximately equal to the best-fit ...
- 11
3
votes
0
answers
35
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Minor inconsistency in Fit/Log
I was trying to fit a powerlaw to some data and noticed some inconsistency in the behaviour of mathematica.
This works
...
- 23.1k
10
votes
2
answers
513
views
Is there a method faster than FindFit to fit conical elliptical cylinder to point data?
I have a code that fits conical elliptic cylinders to point data. It utilizes FindFit.
Usually, I need to fit over 1,500 "cylinders"**, each are ...
- 1,188
5
votes
2
answers
759
views
Finding an exponential curve
I'm working on an exercise in Stewart's Single Variable Calculus: Early Transcendentals, 8th Edition, which asks you to find an exponential curve that fits some data. I tried using the FindFit ...
- 197
6
votes
4
answers
1k
views
How to estimate Taylor series expansion from the function values
I have a function $y=y(x)$ which can be sampled for any $x_i\in (-0.5,0.5)$ with $\epsilon=10^{-10}$ accuracy. I can generate any number of data points $(x_i,y_i)$.
It is known that it can be expanded ...
- 93
7
votes
2
answers
215
views
How to bound a set of data points from above?
The following data produces a distribution as shown. However I want that black-line to be highlighted that is kind of bounding these points from above. How can one do this in Mathematica?
...
- 577
1
vote
3
answers
91
views
How to restrict FindDistribution to real-valued distributions
The following seems buggy to me, but perhaps I'm confused about something. Or maybe there's a workaround that makes it moot?
First, I ask Mathematica to find a distribution that describes a dataset ...
- 696
10
votes
3
answers
1k
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NonlinearModelFit's fit is atrocious
I want to do a very complicated fit (it involves a product of polynomials and non-linear functions).
I read about NonlinearModelFit and thought it would be a good idea to use it. I started with a toy ...
- 1,451
1
vote
3
answers
395
views
Find a fitting function for a strongly monotonically falling function
I would like to find a fit for the following data set. The problem is that I could not find a suitable first guess function. does anyone have an idea?
The problem is that it goes down very sharply and ...
- 141
2
votes
1
answer
162
views
How to fit experimental data using NonLinearModelFit
I am trying to fit the experimental data with the below equation but I am failing to get a good fit
This is the data
...
- 77
4
votes
4
answers
338
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Simultaneous nonlinear fitting of two datasets to two trial functions with shared parameters
I'm relatively new to mathematica and stack exchange.
Problem
Generally my problem concerns finding a simultaneous fit of multiple functions to multiple datasets with shared parameters. I have looked ...
- 317
0
votes
1
answer
48
views
fit a time series with a form containing time as a TimeObject
I created a TimeSeries from TimeObjects (i.e.the list timemeting, times of the measurements) and the measured values (anglesarray). I want to fit the data to a function of time. The function contains ...
- 115
6
votes
1
answer
202
views
VectorAround problem
I am trying to replicate an example give here of correlated variables (it's similar to a more complex problem I'm working on).
I've included the example data and method for convenience:
...
- 720
2
votes
2
answers
183
views
Fitting on Diffraction Pattern, NonlinearModelFit, Complex Infinity
I'm trying to fit the function
$f(x;a,b,s)=a\left( \frac{\sin\left(b \sin(s x) \right)}{b \sin(s x)} \right)^2 $
on the data below using NonlinearModelFit but I'm ...
- 153
1
vote
2
answers
119
views
Nonlinear fit where expression has uncertain numbers [closed]
I am trying to fit my data (which has error) to an expression of the form $y = \frac{a}{(bx+c)^2}$, where b and c are the parameters I wish to estimate. a is a known number with an uncertainty : $a = ...
- 19
1
vote
1
answer
171
views
Fitting a sum of three lorentzian based on a dataset
as you can see below, I have developed a code that allows me to fit the present dataset via a Lorentzian. Now what I should do is to develop a sum of three Lorentzians based on this model so that this ...
9
votes
2
answers
799
views
A strategy to create good initial guess for Lorentzian model fit
I was preparing an answer for a question that got deleted, so I will post this anyhow.
Given a set of data with a hump
...
- 37.4k
2
votes
1
answer
272
views
Fitting a Lorentzian curve to data
Good morning everyone,
regarding my research "high resolution laser spectroscopy" I would like to fit the data obtained from the experiment with a Lorentzian curve using Mathematica, so as ...
0
votes
0
answers
38
views
Evaluate a fit as a function of an argument
I'm trying to manipulate the following function:
...
- 491
1
vote
0
answers
66
views
Error when fitting experimental data containing zero with a log model [closed]
I am trying to fit a set of experimental data with a model using NonlinearModelFit, but I receive an error message that I have been unable to fix. The error message I receive is shown below. Please ...
- 11
0
votes
0
answers
88
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Using MultiNonlinearModelFit with complex data
This is my first question, I'll try to formulate the problem first.
I have a complex function f[z] of a complex argument z which I calculate in Fortran for any z ...
- 93
1
vote
1
answer
50
views
Change domain of kinetic functions in order to fit with ParametricNDSolve
I'm trying to solve kinetic differential equation depended on time with three parameters: preexponential factor a, reaction order ...
- 534
1
vote
3
answers
291
views
The fitting curve cannot be found correctly
I want to fit this function
$$
\operatorname{PF}\left(\sigma_{f_{0}}\right)=1-\exp \left[-\left(\frac{\sigma_{f_{0}}-\sigma_{\min _{0}}}{\lambda}\right)^{k}\right]
$$
I already have some points
...
- 1,630
4
votes
1
answer
569
views
Nonnegative Least Squares Algorithm (NNLS) [closed]
Can anyone optimize the code below which is developed in an old version of Mathematica (2003) both in terms of efficiency and adaption to the latest versions of Mathematica?
Description of the code:
...
10
votes
3
answers
499
views
NonlinearModelFit for nonlinear functions
I am trying to find a nonlinear model from the data.
My code is below:
...
- 1,864
4
votes
1
answer
189
views
Matching a surge function to dataset
I am trying to generate a surge function form of best fit to a dataset using the code from the appendix of https://www.tandfonline.com/doi/pdf/10.1080/10511970608984137.
...
- 41
1
vote
0
answers
325
views
How To Fit Heston Model To Stock Data Stochastic Volatility Model
The stochastic volatility model known as the Heston model can be expressed in Mathematica in the following way
https://reference.wolfram.com/language/example/HestonModel.html
Define the Ito process of ...
- 683
2
votes
0
answers
38
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Function only returns first interpolating function after parameter values specified?
I am fitting data using a system of coupled differential equations and have defined a model function like so:
...
- 409
-3
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1
answer
348
views
0
votes
0
answers
97
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Gaussian fit unable to work
I hace a set of data, each of them contains 101 points. For example, one of them is:
...
- 1
0
votes
1
answer
72
views
FindFit with Replace error
I am trying to fit my data, and I keep having error messages as below. Could anybody help me to solve this problem? The codes are written after the error messages.
...
- 15
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0
answers
42
views
0
votes
0
answers
86
views
Is is possible to specify use of a non-Euclidean norm for NonlinearModelFit
When using NonlinearModelFit with Method->NMinimize I have received the warning message NonlinearModelFit::lmnl, which includes the text
""The model -cVar+Log[1+0.00821596 t] is linear in ...
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