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

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2answers
70 views

What is the role of the pattern object in this implementation?

In the documentation I found a nice idiom which allows me to do model fitting with interpolating functions. I think this kind of thing is amazing and a credit to the utility of an environment like ...
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0answers
28 views

Fitting problem: InterpolatingFunction can not be localised

I got simple data looking as follows {{541.447, 311752.}, {540.359, 311723.},.. I tried to fit it in mathematica for the first time with a function that usually ...
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0answers
36 views

Which one will gives best fitting result?

I want to find out the parameters A, B, and C of the ...
2
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1answer
90 views

P-Values are inconsistent when using DistributionFitTest repeatedly

I am attempting to become more familiar with the DistributionFitTest, specifically the distributions it yields and their fittedness. What I have found is that when I generate random data, fit it, and ...
5
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1answer
130 views

What does LinearModelFit depend on except for its arguments?

I thought this would be always true, but most likely it returns false. ...
4
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1answer
96 views

Substituting ParametricNDSolve for NDSolve

This is my first post so let me know if I need to format things differently. I have been using NDSolve for most problems which optimize parameters for ODEs. I believe that ParametricNDSolve would be ...
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0answers
63 views

Finding values of a variable fitting a function and minimizing a list of expressions

I am trying to implement bootstrapping (https://en.wikipedia.org/wiki/Bootstrapping_(finance)) of CDS curve. To implement it I am trying to minimize a series of expressions so that each expression is ...
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1answer
85 views

Plotting data after fitting it to exponential function [closed]

I am trying to plot h vs t such that h fits a equation ...
4
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1answer
1k views

How does Mathematica estimate error on fit parameters?

When performing a fit using NonlinearModelFit (or any of Mathematica fitting functions, but I am particularly interested in nonlinear models), Mathematica makes a ...
9
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1answer
763 views

How does Mma compute Confidence Intervals?

I am trying to understand how Mma computes the Confidence Intervals after a NonlinearModelFit. Consider the following example: ...
3
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0answers
125 views

Fitting data to a complicated function

So, where to begin. I have a certain dataset that I want to fit to a function. However, the function is rather complicated (matrix inversions, linearsolve) and does in general not have a closed form ...
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1answer
250 views

Fitting data to a circle with FindFit

I'm currently trying to use the Mathematica's FindFit command to fit a curve of some data to the bottom half of a circle. The data is of the form ...
2
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1answer
99 views

Precision of LinearModelFit with Polynomials

I have a Problem regarding the fit of given points with a polynomial up to the fifth degree. tableofvalues=Import["tableofvalues.csv"] My polynomial is: ...
5
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0answers
102 views

Custom Methods for NMinimize/NonLinearModelFit

Is there a way to write custom methods for NonLinearModelFit or NMinimize? To give background, I currently have a batch of code ...
1
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1answer
58 views

Trouble fitting with NonlinearModelFit

I'am having a bit of a headache comparing the results from the NonlinearModelFit to a particular dataset. I have the following dataset, ...
2
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1answer
103 views

Find the best fitting function for some experimental data

I am almost new in Mathematica, and so I have some problems that may appear basic for you. I am given a set of data taken from an experiment. I am supposed to find the curve that best fits them. The ...
2
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1answer
110 views

FindDistributionParameters and Hypothesis Testing

Please excuse me if I am making any logical error in posting this question since I am not a math major. However, let me post my question. I am trying to fit multivariate parametric distribution to ...
1
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1answer
199 views

how to find curve fitting parameters without an explicit relation between x and y?

Let's say I have some experimental data (x,y) and I want to find some fitting parameters. But in my mathematical model, the fitting parameter are not in a simple equation that relates x and y. For ...
0
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0answers
81 views

How to make a twice-differentiable function that approximates some data?

I have some time series data that I would like to approximate with a twice-differentiable function. Each time series has ~10,000 datapoints, so I definitely do not want a function that passes through ...
0
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1answer
231 views

Fitting a theoretical density function with log-return sample

I am working on a exercise to fit a theoretical density function,presented below, with log-return series of a stock. $\frac{1}{2}a e^{a(x-\mu)} \quad \text{if x } < \mu $ or $ ...
6
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2answers
298 views

Find fit of an experimental PDF

After quite some struggle, I managed to put up a code that is syntaxically correct. The goal is to find the parameters for a gamma distribution that best match experimental data. The data is a set of ...
0
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1answer
76 views

How to determine a function that fits a geological model

I have a problem. I am currently working on a code that works by comparing data (real or synthetic) to an earth model (described by earth layers, or in this particular, velocity (...
27
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5answers
2k views

Fitting points to tilted, off-center ellipse

I have 24 x-y points that are supposed to form an ellipse. ...
1
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1answer
82 views

Apply NonlinearModelFit to an image

I have several images (in FITS format), which I want to fit with a 2D-Gaussian distribution. The problem is that NonlinearModelFit expects data in the form of a ...
1
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0answers
46 views

Fit linear data with weights for y and x in LinearModelFit

I am quite new using Mathematica, I hope someone could give me some help. I have a set of {x, y} data and I have a list of {deltaX, deltaY} standard deviation. I would like to fit my data taking into ...
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2answers
218 views
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2answers
3k views

How to fit 3 data sets to a model of 4 differential equations?

I'm a biologist and a newbie in Mathematica. I want to fit three data sets to a model consisting of four differential equations and 10 parameters. I want to find the parameters best fitting to my ...
5
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1answer
224 views

ODE fitting to dataset

So, I have a ODE system, it is a complex biochemical kinetic mechanism with six species changing over time. ...
5
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2answers
562 views

How to fit one distribution to another?

I have a custom distribution created to model some experimental observations. While too complicated to include in this question, I can provide an example and some illustrations to convey a sense of ...
2
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2answers
77 views

FindDistributionParameters gives an error for a mixture of user defined sinh-arcsinh distributions

I have some data (1593 values). I first binned it using the Knuth rule and fitted a function that is a linear combination of two sinh-arcsinh functions. I then ...
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1answer
88 views
3
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0answers
88 views

Fitting data to plot using errors as weights

I have some enzyme kinetics data that I want to fit to the Michaelis-Menten curve in order to obtain the kinetic parameters of the enzyme. Is it meaningful, statistically and functionally speaking, ...
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0answers
52 views

Solve an integral equation: to fit the given data with an integral of two functions?

I am trying to find an efficient way to solve the following equation $$h\left(b\right)=\int_{0}^{b}f\left(\frac{b-c}{1-c}\right)\frac{g\left(c\right)}{1-c}dc$$ where for $h(b)$ I have the data ...
6
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4answers
462 views

How to fit a surface to 3D data in Mathematica?

I have a set of data coordinates which is mostly compatible with an Ellipsoid: {{x1,y1,z1},{x2,y2,z2}, ... , {xn,yn,zn}} Now I want to find the best 3d volume ...
5
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1answer
135 views

Intersection of a ListPlot3D surface with a plane

I'm trying to use Mathematica to analyze some physics data from an experiment, more precisely, I have to fit a 2D data series with a one dimension function. At the moment I'm able to load and plot ...
1
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1answer
270 views

Multiple Linear Regression - obtaining equation with constant term

I am trying to use the LinearModelFit function to obtain a linear regression of my 5 inputs for my single output. I have the input data: ...
1
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2answers
195 views

Is it possible to monitor the sum of squared errors in a NonlinearModelFit or FindFit procedure during the process?

Since fitting procedures using NonlinearModelFit (or FindFit) sometimes take very long, I would like to monitor the sum of ...
9
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1answer
247 views

Least Square Data Fit /Design Matrix

I am trying to learn how to use the DesignMatrix function in Mathematica and how to perform a LeastSquares fit. I am at end of ...
11
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0answers
230 views

Implementation of Partial Least Squares (PLS)?

I'm looking for a PLS implementation for Wolfram Mathematica. I just can't seem to find any implementation for it - do you know one? In general, I'm a bit confused that there exist only so few ...
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2answers
96 views

Does FindFit use symbolic differentiation?

Does FindFit use symbolic differentiation when optimizing by least squares a non-linear function?
0
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2answers
173 views

Least Square Fitting

stuck on a mathematica assignment and could really use some help. A) Fit a function with the shape log(Y) = a0 + a1log(U) to the datapoints (log(Ui), log(Yi) with an least square fitting. Show this ...
0
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0answers
46 views

FindFit returning Power::infy: Infinite expression

So, I'm having an issue trying to fit some data to a function with a 2nd order pole. I know there are other functions that fit the data, just fine ... but the model is from the literature, however the ...
17
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1answer
556 views

Difference between Fitting Algorithms

I am new to Mathematica, and I don´t quite understand, what the difference between the fitting algorithms Fit, FindFit, ...
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0answers
59 views

Investigating the correlation between this 2 set of data

The picture below shows the growth of the traffic and the total number of published articles on that website. Which functions can I use to investigate if there is a correlation between them? Both ...
1
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1answer
63 views

How can I plot more regression trend line in the same graph?

I would like to do something like the example I drawed manually: ...
1
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1answer
73 views

Traffic growth forecast: showing the change of linear regression

The following picture shows a changement in the trend of data. (The data used are available here). Is there any tool that can show this change of trend? Until now I managed to show even more ...