# Questions tagged [fitting]

Questions on the use of Mathematica to construct models for approximating empirical data.

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1answer
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### 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 ...
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 ...
3answers
36 views

### Fitting a function, a (x - 1)^b, to a given set of data

I have some data: ...
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 ...
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Since ErrorListPlot has been superseded by new functionality in ListPlot for Mathematica 12.0, what is the best way to handle ...
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 ...
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 ...
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 ...
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 ...
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 ...
1answer
129 views

### Assign Error bars for y-intercept

I have some data (x,y) with error bars in y direction: ...
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 ...
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 ...
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 ...
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: ...
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 ...
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'...
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: ...
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 ...
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: ...
0answers
42 views

### Best Way For Estimating Parameters Of Hidden Markov Process

Parameter estimation is not stable. First, make a model. ...
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. ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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: ...
2answers
92 views

1answer
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### 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 ...
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/(1 - a*q^2 + b*q^4), where F is the value at zero of a function, which ...
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. ...
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: ...
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 ...
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: ...
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" ...
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 ...
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 ...
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 ...
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. ...
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 ...
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. ...