Questions tagged [fitting]

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

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0answers
35 views

Fitting problem - comparison between two functions

Writing: ...
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1answer
69 views

How to find the fit for a numerical solution

I solved numerically a differential equation and I found a solution (solution that can be plot). I also tried an Ansatz to find an analytical solution and I got an expression. Using the numerical ...
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2answers
111 views

Interpolator surface

Writing: ...
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1answer
180 views

How can I generate a best fit quadratic function?

This is my first time using mathematica so I'm pretty confused. This question is based on the Sierpinski Triangle. The figure below shows the percentage of total even entries and total odd entries ...
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2answers
160 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) ...
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4answers
330 views

Fitting of 2d data points with a function considering scaling, rotation and translation

I have the following set of 2d data points: ...
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3answers
214 views

Exact function that generated the data

I have "data" points as given below (e.g., for x-value = 1, the corresponding value of y is -23.110606616537147. (I apologize, it is rather large data array.) I need to find out the exact function ...
4
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2answers
856 views

Multi peaks fit (Voigt, Lorentzian or Gaussian)

I have started quite recently to use Mathematica and I don´t have experience in coding. What I need to do is to fit a peak which probably is a combination of two Voigt or Lorentzian. I have tried ...
4
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3answers
546 views

How do I find the root mean squared error of this fit?

I have the following data. ...
2
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5answers
179 views

Making batch data fitting robust — why does `NonlinearModelFit` fail occasionally?

I have over 1000 spectra I would like to batch fit and then use the results for further study. I'm not fitting anything especially complicated just a Lorentzian of the form, $$y(x) = A \frac{\gamma^{...
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0answers
40 views

Define output as the input

I want to find fitting parameters and then I want to use those parameters my further calculation. I used the following command for the fitting and I got values for the parameters. How should I define ...
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3answers
221 views

Automatically fiting experimental data using NonLinearModelFit

Please, I have been working for some time to perform an automatic fit of my experimental data using an analytical function developed from a model based on the theory of kinematical diffraction. The ...
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1answer
79 views

Gaussian fit with two variables

If I have an expression where two unknown parameters and a certain range of one parameter are present then how I can get best fitted values of such two parameters by varying this range?
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1answer
101 views

Properties of an arbitrary (i.e., not fitted) statistical model

Suppose that I have a data and a statistical model that is not the result of fitting, but has a different origin. For example, I have a list of measurements and a ...
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1answer
56 views

Fit data with a given function depending on parameters

I want to fit the data of a star's temperature with a function from a model. That function depend on several parameters. I want to know how can I find the value of those parameters. The data is: <...
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1answer
131 views

Fit this data to a model in mathematica [closed]

I need to find a distribution or a model to fit this data set in Mathematica ...
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2answers
97 views

Obtaining the polynomial describing the motion

I have the following data points: Clear["Global`*"] dados={{0,0},{1,1000},{2,-750},{3,250},{4,-1000},{5,0}}; From these data I obtained the following ...
2
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3answers
173 views

How to get a plot with more precision in the data points?

Working with other software called SolidWorks I was able to get a plot with a curve very close to my data points: I tried to get a plot as accurate as this, but using the ...
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2answers
125 views

How to draw lines connecting nearby points [duplicate]

Suppose I have the following example data, data = Table[{Cos[theta], Sin[theta]}, {theta, 0, 2 Pi, Pi/8}]; which, when plotted, looks like this, ...
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2answers
103 views

Listplot, Plot and e function bug

For a project I have, I have let a program calculate required interias and friction for my system are R and J in the params. That program calculated 0.5*10^-3 and 0.013~ respectively. I'm trying now ...
2
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2answers
80 views

NonlinearModelFit doesn't seem to work with inverse function - please help!

I have the following defined: lvf1 = Table[{i, 1/(10 - i)}, {i, -100, 100}]; If I just run this, it gives me a "Power: Infinite expression 1/0 encountered." ...
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1answer
98 views

Linear mapping to fit points to subset of other points

I have some set of points making a specific pattern. I want to find a linear mapping (dilations + translations) to find a similar pattern in a second larger set of points. I want to find the best (or ...
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1answer
84 views

Forcing a 2D nonlinear fit through a set of points

I am trying to fit a set of data points using exponential functions as the underlying process suggests an exponential decay. The data points are: ...
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2answers
713 views

Fitting PDF to two normal distributions

I'm trying to fit this data As you can see there's two peaks. I want to fit this curve with two normal distribution with the same variance but different mean. So far I've got this: ...
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1answer
250 views

How do I access individual groups after using GroupBy on a Dataset object?

I want to read in an xlsx (Excel) or TSV (tab-delimited) file, assuming this results in a rectangular table of data. Then I after applying GroupBy (using multiple keys), I should have several ...
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1answer
267 views

Find interpolation with derivatives at some points

I am trying to find out how to find a good interpolation of a periodic function I have from some data points. The only problem is that I need to make sure that derivatives at the starting and ending ...
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2answers
279 views

Problem in using FindFit

I have the following set of data data={{0,0,0},{0,2,1},{0,4,2.247},{0,6,3.627},{0,8,5.031},{1,0,3.346}}; where the values are {n, L,$\varepsilon$} and satisfy ...
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1answer
90 views

How to find minima for non scalar-valued [closed]

I want to find minima. My code: ...
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1answer
53 views

How to pass starting values in matrix form?

Consider the following MWE, where I try to pass starting values to FindDistributionParameters[]: ...
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1answer
570 views

What are the practical differences between Fit, NonlinearModelFit, and FindFit

What are the practical differences between: FindFit,NonlinearModelFit,and Fit. Do they call ...
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2answers
78 views

Evaluating a formula that uses summations and products of vectors

Could someone tell me how to find beta1? I have the following data: I don't know how to write beta1, and I don't find anything ...
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2answers
64 views

Difficulty fitting an equation to a data set using exponential growth and logistical growth [closed]

I'm having an extremely hard time getting linearmodelFit, findFit, or nonlinearModelFit to give me an output that I can work with and I can't seem to find the problem. My list is ...
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2answers
106 views

Partitioning Mixture Distribution Dataset into constituent Distributions

Suppose I have a dataset that is derived from a random sampling from a mixture distribution ...
1
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1answer
90 views

Estimation of the error for zero degree of freedom fit with error bar

I am performing a fit on experimental data with zero degree of freedom but with error bar using NonlinearModelFit: ...
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1answer
182 views

Problem with fitting square root-like function

I have following data: ...
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0answers
45 views

Simultaneous fitting of polynomial parameters to data [duplicate]

I have two following data-sets: ...
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1answer
87 views

Fitting complex equation

I used the following code for fitting but it does not produce an output.I kept it nearly 3 to 4 hours but it does not give any output. How should I make it correct?I have used two equation(f1,f2).I ...
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1answer
300 views

How to do good surface fitting in Mathematica?

I would like to fit a 3D surface in Mathematica, and I can do a rough fitting using the following code: ...
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0answers
88 views

Surface fit in Mathematica for sigmoid type of surface

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1answer
54 views

Get properties of a list of fitted models (objects)

If I do a fit, such as nlm = NonlinearModelFit[data, {x^a Cos[b x + c]}, {a,b,c} ,{x}] then you return a FittedModel object, ...
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1answer
64 views

Unable to understand how FindFit function works. [closed]

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1answer
129 views

Problem using Nonlinearfit on integral function

I tried to fit my data with a very complicate Integrated function. But I get many errors messages when I perform the fit. For exemple I get : NIntegrate::inumr: The integrand ....has evaluated to ...
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1answer
246 views

Model fitting for concave curve: test if asymptote or convergence exist

I am asking a double check if conceptually I set up proper model and proceeding in good direction to drive conclusions. I have a distribution that looks like this: I want to test if for increasing x ...
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1answer
426 views

Fit Gaussian Function [duplicate]

I want to fit the Gaussian Function for the following data. How should I do it? ...
12
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1answer
421 views

Quantile Regression using Neural Networks (Custom Loss function)

I would like to perform a Quantile Regression within Mathematica's neural network framework. Since there exist a couple of tutorials for this exact problem in Tensorflow, i.e. Deep Quantile ...
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1answer
47 views

To fit a curve , the plot is in LogLinearPlot. I am trying to fit an equation for this curve

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5
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2answers
130 views

Why does the PearsonChiSquare from FindDistribution and DistributionFitTest differ by a factor of $10^{20}$?

This is similar to the unanswered "Why the results of FindDistribution and DistributionFitTest are not consistent?" My more specific question is: Why do the PearsonChiSquare values for ...
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1answer
65 views

What is the best fit for this data?

First I entered the data and graph it, then I used the non-linear adjustment command to have a model of my data, I asked Mathematica for the square r, to know how good the model was, then I put ...
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1answer
276 views

Linear regression with weighted data?

LinearModelFit doesn't seem to support WeightedData objects. Is there anything I can do smarter than repeating the data ...
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2answers
107 views

FindFit cannot give me the right result. What should I do?

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