Questions tagged [fitting]
Questions on the use of Mathematica to construct models for approximating empirical data.
1,156
questions
2
votes
1answer
211 views
Standard error of a nonlinear fit
I would like to better understand the process that Mathematica uses to determine the standard error when fitting with NonlinearModelFit. I have been reading this ...
2
votes
0answers
26 views
What are the most reliable test of goodness of fit in Mathematica
I realise this is possibly a VERY open ended question, and potentially has answers dotted around e.g. here
.
What are the most robust methods of testing the result of ...
1
vote
3answers
36 views
0
votes
1answer
36 views
Problems with NonlinearModelFit: “..is not a real number at ” [on hold]
I am a newcomer to Mathematica. Basically I just want to fit the data shown below (ArrayFVel). Unfortunately, the model contains rather complicated integral that ...
11
votes
1answer
173 views
What is the best way to use errors in mathematica M12?
Since ErrorListPlot has been superseded by new functionality in ListPlot for Mathematica 12.0, what is the best way to handle ...
1
vote
1answer
42 views
Combining fitted parameters to make a variable and telling me the error in it
I've fit my set of data to a function of the form: $a*\cos(2\pi t)+b*\sin(2\pi t)+c*\cos(4\pi t)+d*\sin(4\pi t)+e$ with a nonlinear model fit. The parameters $a,b,c,d,e$ have errors in it that ...
2
votes
0answers
42 views
How can you set the fit tolerance in `NonlinearModelFit`?
In NonlinearModelFit how can you set the tolerances of where the fitting terminates. I know you can set MaxIterations but how ...
0
votes
1answer
71 views
Nonlinear fitting does not perform appropriately
I have a list as below one:
mustbefitted={{0., 1.}, {4.4, 0.982211}, {8.9, 0.961575}, {13.3, 0.942571}, {17.8, 0.923857}, {22.2, 0.906203}, {25.1, 0.046994}};
I ...
0
votes
1answer
60 views
Fitting data with NIntegration related function
I am trying to fit experimental data with data file given below function, but I am not able to find the best fit. Constant value is A=6.26 and ...
15
votes
2answers
898 views
Does anyone have experience with performing symbolic regression using Mathematica?
I understand that there is at least one Mathematica package, DataModeler commercially available for symbolic regression. I'm seeking any observations with this or any other similar tool.
I'm ...
5
votes
1answer
129 views
0
votes
0answers
26 views
No progress on validation NN training set
So in short my issue is that I'am training a neural network and while the training loss reduces over time, the loss of validation set remains constant.
The progress of training looks like this:
I am ...
32
votes
1answer
1k views
How to fit a linear model in the Bayesian way in Mathematica?
Basically, I'm looking for the Bayesian equivalent of LinearModelFit. As of the moment of writing, Mathematica has no real (documented) built-in
functionality for ...
0
votes
1answer
54 views
Obtain reduced chi-squared for fit
Dear Colleagues,
I have performed a fit according to the code below. The last step is to obtain the value for the reduced chi-squared for the goodness of fit. Does mathematica have a ...
0
votes
1answer
46 views
How to fit data with superposition of CDFs?
With the help of @JimB, I could fit some experimental data with a CDF using NonLinearFitModel. The set of data is the following:
...
2
votes
2answers
106 views
Fitting two-dimensional data
For this question, I cannot use random sample data. So the actual data can be found here. The data file contains three columns, where the first two are the coordinates $(x,y)$, while the third is the ...
0
votes
1answer
64 views
Fitting nonlinear function does not converge but looks close to best fit
I'm having trouble fitting this transition temperature equation to my data. Physically speaking, the intensity should flatten out for T>Tc, which seems to be the biggest problem here. The equation I'...
1
vote
2answers
80 views
Getting error General::munfl from NonlinearModelFit [duplicate]
I am trying to fit data to a sum of Gaussians.
This data is found in a file called lpeff.txt. So I write the following code:
...
0
votes
0answers
40 views
Fitting data points with a function obtained by ParametricNDSolve+Integrate
My question concerns fitting data points to a function that is a solution of a set of parametric differential equations, then integrated over time. More specifically, I have these parametric ...
0
votes
2answers
52 views
How to find the best quadratic fit for a set of data?
I'm trying to find a degree-2 polynomial fit with x-intercepts of x=0 and x=1 for the below set of data:
...
1
vote
0answers
42 views
Best Way For Estimating Parameters Of Hidden Markov Process
Parameter estimation is not stable.
First, make a model.
...
0
votes
1answer
44 views
Using NonlinearModelFit function with polynomial I have defined
I have a data set that I wish to write a loop for to fit polynomials to. I want to be able to type in the max order polynomial I want it to calculate the fit for and have it solve each along the way. ...
3
votes
1answer
68 views
Choosing the best fit from given plots
I have some data:
x={1,2,3,4,5,6,7,8,9,10}
y={3.05,21.05,69.05,162.05,315.05,543.05,861.05,1284.05,1827.05,2505.05}
That I plot with ...
1
vote
1answer
75 views
Fitting tail of distribution to Generalized Pareto Distribution
Hello, I have a problem in Mathematica and I don’t know if you could help me. I’m trying to compare the “performance” of a Laplace distribution and a Generalized Pareto Distribution (GPD) for the tail ...
2
votes
1answer
53 views
Put error bars in a plot from a non-linear fit together with confidence level
I want to ask you a problem that I have. I make a non linear fit with some data, and I want to know how can I put the error bars in the plot together with the confidence level of the fit that I ...
20
votes
2answers
923 views
Curve fitting by running through hundreds of models and return the one with best fit
In the past, I used to solve a lot of my regression analysis (curve fitting) problems with a program called DataFit which runs on Windows. It has hundreds of regression models which it runs through in ...
0
votes
2answers
54 views
FindDistributionParamters vs. NonlinearModelFit for NormalDistribution
I have the following data:
dat["Sag"] ={1.277, 1.913, 1.48, 1.472, 1.787, 1.736, 1.896, 1.715, 1.131}
I want to fit a normal Distribution to it and get the ...
4
votes
1answer
46 views
Partial and semipartial correlation
I am interested to know if there are built-in Mathematica functions that performs partial and semipartial computations.
If not, what would be a simple and efficient way to compute them from the ...
0
votes
1answer
73 views
Getting errors from ParametricNDSolveValue
I am a newcomer to Mathematica (use ver 9.0).
I just want to fit the experimental data to a system of odes' by using NonlinearModelFit. The data, contains time in the first column and product ...
3
votes
1answer
110 views
Fitting a mixture of two normal distributions for a data set?
EDIT: Raw data can be found here: https://gist.github.com/Kagaratsch/65a931d8d78fcdd81f7e346429a02afd
Consider the following binned example data:
...
0
votes
2answers
92 views
FindFit or Integration Making Use of NumericQ Not Converging
Hello Mathematica Users,
I'm using ?NumericQ to solve an integral numerically and then fit the data to give me values for certain parameters.
The integrals involved appear in:
$$
\alpha = \frac{...
9
votes
2answers
775 views
Fitting experimental data by using ParametricNDSolveValue and NonlinearModelFit
I am a newcomer to Mathematica.
Basically I just want to fit the data (enzyme kinetic data) shown below to a system of odes' by using NonlinearModelFit. The data, an 101x2 array, contains time in the ...
0
votes
1answer
70 views
Goodness of fit : how to perform weighted Pearson test (or equivalent)?
I wish to perform goodness of fit. Currently I use NonLinearModelFit :
...
0
votes
0answers
82 views
Problem with fitting
So I have a very simple question related to a simple topic, but also directly related to a fitting problem.
I see that my question is related to this question but I don't manage to make the bridge ...
1
vote
1answer
57 views
Finding a fit with a specific mean squared error
I have a fit a data set to the following equation
...
0
votes
2answers
137 views
Fitting data using a parametric differential equation
I was fit the data using differential equation(eqns) and pfun
I tried data fitting (I gave the parameter directly..a=22500, b=10^-22, c=2*10^-40 and scaling factor k=1.04 10^-36)
...
1
vote
2answers
164 views
Dynamic number of parameter fits in Mathematica
I am trying to learn if in Mathematica one can perform fits of analytic functions that are expanded and written as power series. In particular, we can consider the following generic form:
$$
f(B,x) = ...
2
votes
1answer
110 views
Why doesn't Mathematica completely draw the fit?
I have a question, and I really need your help, because I think I'm not understanding the reason...
I have a potential model..
F[x_] := k x^n
for the next ...
1
vote
1answer
56 views
How to fit a list of points to a certain form given error bands?
I am trying to fit a list of points to the form F[0]/(1 - a*q^2 + b*q^4), where F[0] is the value at zero of a function, which ...
1
vote
0answers
44 views
Fitting a Curie-Weiss law function with a diverging point to a data
I would like to fit a function to some experimental data such that the extracted value of Curie temperature (Tc) describes the temperature at which the response flattens out to a constant value. ...
0
votes
0answers
63 views
Why does ListSurfacePlot3D yield a different surface fit than using Python code for best-fit quadratic curve (2nd-order)?
Using the same data, I obtain different surface fits on Mathematica (using ListSurfacePlot3D) and Python (using a code for best-fit quadratic curve (2nd-order)).
Here's my code on Mathematica:
...
5
votes
2answers
187 views
NonlinearModelFit when the fitting function produces a discrete list of values?
Short Version: I have a parameterized function (the model) that returns a list of values. I have data that I want to fit this model to, optimizing those parameters, where the list position in the data ...
0
votes
1answer
42 views
How to extract parameters from fitted model for ListSurfacePlot3D?
I would like to obtain the parameters used by Mathematica to create this surface fit of 3d data:
...
4
votes
3answers
109 views
Tangent point coordinates when the curve is a set of points
I want to find the coordinates of the tangent point between a convex curve and a line that passes from a point with known coordinates (0,b) ("efficient portfolio" ...
3
votes
0answers
47 views
BSpline vs natural spline [closed]
The BSpline in mathematica is defined mathematically here. These BSplines constitute basis for any Spline. But how do I define natural splines in mathematica, i.e. splines that are linear left of the ...
14
votes
3answers
1k views
2D smoothing spline interpolation
Does Mathematica have 2D smoothing spline interpolation built in?
I requires an interpolation method with smooth first derivatives and cubic bivariate splines fulfill this nicely. In python I would ...
0
votes
2answers
57 views
Accessing nonlinear fit coefficients
I have performed a nonlinear fit onto a set of data according to the form
$a+b\cos(2\pi x)+c\sin(2\pi x)+d\cos(4\pi x)+e\sin(4\pi x)$. How do I access the best fit parameters $a,b,c,d,e$, store them ...
1
vote
1answer
41 views
Why UnitCovert doesn't work with Fit?
I need to find the Hubble constant (Ho) in light years, from some data, the exercise tells me that the constant of the hubble is the slope of the line.
data:
r1 is in MegaParsecs.
...
2
votes
4answers
209 views
How to superimpose a curve fit on top of a TimeSeries plot?
This is a remarkably simple question for which I was not able to find an answer in the documentation.
For concreteness, suppose that we have some time series data, such as this (example taken ...
8
votes
1answer
192 views
Fitting multiple data with model and NDSolve with different initial conditions, and other shared parameters
I know that there are already questions about fitting multiple datasets and about NDSolve and about shared and non shared parameters, but I tried to apply them and some things are still not clear.
...
