Questions tagged [fitting]
Questions on the use of Mathematica to construct models for approximating empirical data.
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2answers
120 views
How to do an exponential fit for this data?
Whenever I try to use FindFit or NonlinearModelFit for the data (shown below), I keep getting the following error thrown at me:
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2
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1answer
85 views
What is FindFormula returning?
I was playing around with FindFormula and am experiencing some odd behavior.
I am running MMA 12.0.0.0 on a Windows 10, x86 architecture - if that matters.
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0
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0answers
19 views
Covariance matrix from FindMinimum
Despite checking for quite some time online and in the docu, I cannot find an "easy" way to get the covariance matrix from FindMinimum.
When FindMinimum has reached the local minimum, it returns the ...
0
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0answers
39 views
Well calculated Root Mean Square?
I am trying to estimate root-mean-square of data and fitted curve.
However, i don't know it is working well or not.
Can you guys give me any idea?
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0
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0answers
59 views
find gravity acceleration (g) using FindFit
I need some help again, with this simple exercise:
Use the data to determine g, but this time use the functional form T = 2 pi Sqrt[L/g] for the period T of a ...
1
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2answers
79 views
Fitting experimental data with a parametric function
How does one use a fitting routine such as NonlinearModelFit with a ParametricFunction? Example below:
First let's generate some data:
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1
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1answer
54 views
Help with NonlinearModelFit Error
I would like to ask if anybody can help me to find a way around solving this problem in Mathematica. I've tried solutions I found here but they don't seem to work. I need all the help I can get. ...
4
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2answers
99 views
Non Linear Model Fit - Fitting ODE to Data
Thank you everyone for your meaningful contributions!
My Goal and Problem
I'm trying to fit a particular ODE in a set of ODE's to experimental data. I've attempted to implement this by following the ...
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2answers
47 views
Estimating the uncertainty in the slope of a straight line given the uncertainty in the data points
Basically I have some datapoints on the form $(x_i,y_i)$
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0
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1answer
79 views
How to find a formula that models this plot? [duplicate]
Here is the data that I used to get this plot:
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0
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0answers
53 views
Can Mathematica be used to fit these functions related to the Riemann Xi function $\xi(s)$ to a known probability distribution type?
This question is related to my Math Stack Exchange question at the following link:
Question on Probability Distributions Related to the Riemann Xi Function $\xi(s)$
The definitions below are for $x&...
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0answers
59 views
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0answers
40 views
What is optimized for each available FitRegularization setting?
Fit and FindFit now have a FitRegularization option, but the documentation is brief. What is optimized/minimized when each available setting is used?
1
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1answer
62 views
Weibull statistics
I have two data sets am interested in finding the weibull modulus and characteristics strength for the two data sets and plotting the data seperately but on the same graph
Material (a)
723, 684, ...
6
votes
1answer
223 views
How could this asymptotic expansion be obtained?
I must precise that I am a very limited user of Mathematica (I can only run it from time when going at university).
Working this problem, I found that
$$\sigma_n=(1)^n\frac{\pi}{2} \big( j_{0,n+1} \,...
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0answers
43 views
Force FindFormula to avoid Piecewise in the result?
Is it possible to provide any arguments to FindFormula to force it to avoid using Piecewise in the result, but instead try to ...
-1
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1answer
41 views
1
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0answers
36 views
Getting a PDF from a NonlinearFitModel
With the help of @JimB, I could fit some experimental data with a CDF using NonLinearFitModel. The set of data is the following:
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0
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2answers
63 views
How to generate two non-overlapping LogNormalDistribution and their CDF?
I'd like to know how to generate two LogNormalDistribution with the same standart deviation and, if possible, get the associated CDF.
To contextualize, I'm trying ...
0
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0answers
35 views
How to fit experimental data with by numerical integration?
folks.
I'm a begginer with Mathematica and all I know is just a few basics commands and i'm trying to improve it.
I have this list of experimental data taken from a paper which describes the ...
0
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1answer
50 views
How to fit one function into the form of another?
I have a slightly complicated periodic function of one variable t, say g[t].
I want to do a least squares fit of that function ...
0
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1answer
33 views
Table and NonlinearModelFit
I am trying to make data and fit it tp a power law model. but it doesn't work. I don't know what the problem is.
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0
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0answers
63 views
How can I fit a function to another function?
I want to fit the gaussian function to power law function from the end of gaussian fitting curve to the peak of it,
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0
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1answer
68 views
Model for log-inear data
I am trying to fit the following data with y axis on a log scale. I used the following model to fit the data but without success.
Can anyone help me suggest a proper model?
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2
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2answers
72 views
1
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1answer
65 views
Curve Fitting using known Points [closed]
In this answer, David Stork said that my question could be solved using "simple curve fitting with different numbers of even polynomial rank" in Mathematica. How would I do that (an equation that goes ...
1
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1answer
64 views
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0answers
40 views
Creating a prediction/distribution based on several years of data
So I have several years of data from a survey. For each year I've used FindDistribution and Predict to see if I can fit the data. Here's one example
Where I used FindDistribution to get
...
1
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1answer
103 views
How to fit my data to an ode
Here is system of ODEs and data, where I am trying to use the real data to estimate some governing parameters.
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0
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1answer
55 views
4
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0answers
94 views
0
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1answer
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Method for constrained NonlinearModelFit with NDSolve
I'm trying to fit some data with a system of differential equations :
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0
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1answer
48 views
0
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0answers
43 views
Estimated LogMultinormalDistribution
How to use procedures designed for EventData for an event data in the bivariate form?
That means the bivariate data containing each of the four combinations ...
1
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1answer
56 views
Least squares fit of a symmetric linear system
I have $q$ measurements with $p$ different excitations.
In one special case, they might be equal in length. For example, I might have 12 measurements ($q=12$) with three excitations each ($p = 3$), ...
1
vote
1answer
65 views
How do I separate all local maxima and local minima of my function?
This question (and the first answer in particular), teaches us how to find all the local maxima and minima of a function.
My question is: how can I separate the maxima from the minima? My goal is to ...
1
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2answers
43 views
Using FittedModel without clashing symbols
For some FittedModel, the "BestFitParameters" are given in terms of the symbols used to define the model.
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2
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1answer
85 views
How to reproduce old SplineFit function?
Prior to version 8, Mathematica included a SplineFit function that could be used, for example, in the form:
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0
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1answer
68 views
How to do a fit on multiple peak with a voigt function
I looked a lot on the other questions to do that but I can't find a way to do it properly. So here is my question. I have a spectrum of OH and I would like to do a voigt fit on every peak it has to be ...
3
votes
2answers
185 views
Determining multivariate least squares with constraint
I have some composition data for a geological sample and its constituent minerals. I want to estimate the proportions of the minerals that make up the bulk sample. This is essentially a mass balance ...
1
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1answer
58 views
Attaching independent variable values to data for curve fitting
I have a data set of $10^4$ entries. I want to plot the last $2000$ data with the same argument at $x$ axis and fit a curve. That means the range of $x$ axis will be $8001$ to $10000$ incremented by $...
6
votes
2answers
137 views
How to speed up Voigt profile fits?
Voigt profile fits in Mathematica seem terribly slow. For an example data set with 81 points a corresponding fitting procedures for Voigt fits is >1000 times slower than for Gaussian or Lorentzian ...
3
votes
2answers
72 views
Generating FittedModels from vector-valued linear model fits
I have vector-valued data with normally distributed noise that I want to analyse. Assumptions on data can be made; in this specific example, it's expected that components of fitted vector values ...
3
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1answer
51 views
Using an offset variable in a Poisson GeneralizedLinearModelFit
In section "2.6 Exposure: Modeling Over Time, Area, and Space" of his book "Modeling Count Data" Joseph M Hilbe uses an offset (exposure) variable in his Poisson regression analysis of the FASTRAK ...
2
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1answer
59 views
Fitting data with 3 linear fits
I have a dataset that can be easily approximated by a piecewise function composing of 3 linear functions, but i am unable to get an accurate fit once the third linear function is required. The model ...
0
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0answers
51 views
Peak convolution
I am not an expert of wolfram mathematica, anyhow I decided to use it to perform analysis on some data I acquired. I found on this website a question about how to do peak deconvolution and I tried to ...
3
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1answer
74 views
What is a proper way to represent multidimensional data in TemporalData?
A TemporalData object can host multiple paths or it can admit a ValueDimensions option value greater than unity.
In the former ...
0
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0answers
42 views
fitting different data sets with one same model with NonlinearModelFit [duplicate]
I have a bunch of list data sets, like 6 or 8 of them. They are 2D and look similar. Both x axis and y axis have variance (in each measurement, x axis also changed a little bit).I know the fitting ...
5
votes
1answer
340 views
Should a new user just default to LinearModelFit (vs Fit) [duplicate]
I tried searching but the noise in the responses is high due to 'fit' being both a function and a valid term.
If I'm new to Mathematica should I just default to ...
3
votes
2answers
102 views
Optimize/fit data for 2 variables described by three functions
I have three equations that describe how parameters change:
$$N_{1}(T,f)=f \ e^{-T (\sigma^{1}_c +\sigma^{1}_f)}$$
$$N_{2}(T,f)=-\frac{f \sigma^{1}_c \ (e^{-T (\sigma^{1}_c +\sigma^{1}_f)}-e^{-T \...
