# Questions tagged [fitting]

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

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### Fitting 3D data with a nonlinear model

I am trying to fit a model to an intensity map to extract three values for the parameters of my model $J_x, J_y, J_z$. Currently, I am running into the issue where I can extract values for these three ...
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### How can I minimize a target function that has to solve differential equations numerically?

My problem is to minimize a target function with differential equations in it. The target function is $$\min \mathrm{J}\left( p \right) =\sum_{i=1}^5{|x_i\left( p \right) -y_i|},$$ where $x_i(p)$ are ...
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### How to optimize variables in a function to minimize its difference with the desired behaviour function

So lets say I have a function f(x,y,z,b) and a function g(x) that represents the desired behaviour of function f. How do I optimize the variables y,z,b in function f to get as close as possible to ...
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### Finding distribution parameters of a gaussian mixture distribution

Short version: how to estimate the parameters of a mixture of multivariate normal distributions (i.e.: Gaussian mixture model)? Long version. I am trying to estimate the parameters of a mixture of ...
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### Fit and Data in (1/x,-Log[y])-Scale

I have data as a list of xy-pairs, but have to plot it in {1/(x), -Log[y]} space. I am also making a fit to the data, so I used the raw data for my fit and I used <...
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### Regression of a set of (2-element) vectors on another set of (2-element) vectors

As a trivial example, here are two vectors: f = {{1, 1}, {2, 2}, {3, 3}, {4, 4}} s = {{-1, 2}, {-2, 4}, {-3, 6}, {-4, 8}} It is instantly clear (apart from my ...
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### 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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### ProbitModelFit is causing kernel crashes in Mathematica 12.0

Mathematica 12.0 I am running ProbitModelFit on a small data set (~130 rows). Intermittently, the function causes a kernel crash. I am curious if anyone else is ...
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### (Non)LinearModelFit hangs on “trivial” linear fit (Fit succeeds)

A simplified version of my function and a simplified subset of my data (real data also has weights, if that matters, but I tested both with and without those): ...
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### Problem with parameters from fitting

I am trying to fit the following data (called TflogqIND): ...
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### finding FWHM of a dataset with unknown mathematical equation

I have a dataset. I have plotted using "Listloglinearplot". Now I need to find the FWHM (full width half maxima) of the same, However I dont know which mathematical eqution describes best to ...
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### Chemical Kinetics: fitting multiple sets of time series data using multiple differential reaction equations

Let me start by saying that this is my first post, so if there are suggestions on proper formatting that is annoying you, please let fly and I will do my best to modify. I was doing well solving the ...
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### Find Fit error 4P logistic

I am trying to fit a four parameter logistic curve to my data set. I have the estimated values for each coefficint, but it says the jacobian is not a matrix... Here is my data: ...
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### Fitting for constants

I have this differential equation: $$m\ddot x=-kx^\frac{3}{2}-c\dot x-mg$$ where I want to fit for $k$, $c$. ($g$ is 9.81 and $m$ is 0.3). This is a model for collision, hence in the data that we have ...
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### Multinomial logistic regression

Has anyone done multinomial logistic regression in Mathematica? The binomial case is essentially done on the LogitModelFit documentation page and works fine. I am ...
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### Find coefficients of a periodic function with non-linear fit [closed]

Description of the problem: I'm studying a signal that is the sum of two exponentials at two different frequencies: $z(n) = A_1*e^{2\pi i\nu_1n } + A_2*e^{2\pi i\nu_2 n } + noise$ The signal itself is ...
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### Problem creating MeanPredictionBands

I have a problem creating MeanPredictionBands for my function which I fitted using NonlinearModelFit. I have a complex-valued ...
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### Linear regression, numerical integration and non-specific fitting

I am still pretty new to Mathematica. I am numerically integrating a function that we can consider as NIntegrate[f[z] g[z], {z, 0, 1}] so that, when I put in what I ...
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### Confidence Interval Table

I estimated parameters using a transcendental function in the model. The estimate worked using the following commands: ...
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### Fitting model to data

I have been trying to adapt some of the previous suggestions on other questions similar to my problem but I haven´t been able to solve my problem so far. Best wishes
995 views

### Mathematica Interpolation or approximation

I have lists of points X and Y. {1212,1216,1217,1219...}, {1,2,3,4,5,6...} I combine ...
575 views

### Curve Fitting Data using Polynomial

I have this data set in Mathematica: ...
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### Finding astroids

An astroid is a particular mathematical curve: a hypocycloid with four cusps. Given a lot of data points I'm trying to fit such a curve to the data. As an astroid is also an algebraic curve of grade 6 ...
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### 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 ...