# Tagged Questions

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

108 views

I'm in a little over my head here and I'm fully aware of it, so I'm hoping for some help. I've been assigned to a project where I am given data: http://www.pastebin.ca/3061136 (Example Data) I ...
346 views

### Fitting and plotting Weibull distribution

How can I find the best fitted 2-parameter Weibull's distribution (PDF) to describe my data? How can i plot my data and estimated distribution all in one graph? How can I show/compare results of ...
87 views

### Using FindFit for a non-trivial complex function [duplicate]

I have data set which I would like to fit to the function $\quad \quad f(r) = A\cos(kr - \pi/4 + \phi_1)\times\exp(i(-2\log(r) + \phi_2))$, where $k$ is a constant I know and $(A,\phi_1,\phi_2)$ are ...
210 views

### Fit model with two dependent variables

Say I have an experiment that produces two values, for a given input. For example you get a complex response value. Now I have a model that - of course - also produces two dependent values for one ...
168 views

### Curve fitting data I imported from excel [closed]

This is my first time posting here, so sorry if I break any rules. There is this excel document from which I imported two columns of data to mathematica. I need to fit the data into a curve so that ...
56 views

### Mapping Linear Model Fit Over An Arbitrary Number of sets

I have multiple sets of data, and I want to apply Linear Model Fit sequentially to each set of data. For example, below tstlst contains 3 data sets. Right now I ...
809 views

### Fitting - Exponential

I'm trying to fit the following data using Mathematica, but unfortunately im not getting any decent results. ...
102 views

### TargetFunctions option in FindDistribution yields error

I have some data set that I am trying to find the maximums . I figured I could do this by fitting the many peaks of the dataset to Gaussian distributions and then finding the peaks of this data from ...
236 views

### Solution to heat equation with Neumann boundary conditions and lateral heat loss

I am conducting an experiment on heat conduction in a copper rod. To do so I am using a thin copper rod with several temperature probes, then I am going to compare the data with a solution to the heat ...
470 views

### Find a Fourier series from discrete data

I am trying to fit a Fourier cosine series to discrete data. I read through this, but I was not able to understand it. The data should be periodic with a period of $0.2 \text{ m}$, and it is the ...
188 views

### NonlinearModelFit errors and precision

For this problem, I use a data set, which I've made available here. ...
138 views

### Non Linear Model Fit (Division by Zero Error Message)

Can someone please tell me why this expression returns error messages about division by zero. ...
76 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 ...
42 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 ...
103 views

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114 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 ...
119 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 ...
86 views

### Finding values of a variable fitting a function and minimizing a list of expressions [closed]

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 ...
103 views

### Plotting data after fitting it to exponential function [closed]

I am trying to plot h vs t such that h fits a equation ...
310 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 ...
114 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: ...
78 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, ...
258 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 ...
143 views

### Find fit does not find the best fit

Here is my data ...
92 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 ...
127 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 ...
86 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 ...
118 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 ...
317 views

### ODE fitting to dataset

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

### Fitting data to plot using errors as weights [closed]

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, ...
251 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 ...
156 views

### non linear Least Squares with model function given by ODE's

I have to fit to experimental data a model function given by a linear combination of functions y1(t) and y2(t) a1*y1(t) + a2*y2(t) with a1 and a2 ...
114 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: ...
101 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 ...
342 views

### TimeSeriesModelFit incorrect?

I am trying to determine the optimal model for time series data (1592 observations). When I run TimeSeriesModelFit, Mathematica selects $AR(1)$ model, the estimated ...
329 views

### How to Fit experimental data with 4D ParametricNDSolve?

Let me first explain the background problem. I'm trying to solve a problem with a projectile motion in 4D such that the position vector is: $\boldsymbol{r}(t)=\boldsymbol{r}[x(t),y(t),z(t)]$ I have ...
149 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 ...
249 views

### NonlinearModelFit and plot with multiple parameters function

i ve got quite simple function: $f(t) = x1 * a(t) + x2 * b(t)$ and table of results like this one: t | f(t) | a(t) | b(t) ---------------------- 1 | 2 | 5 | 3 ---------------------- 2 | 4 ...
73 views

### Fitting a vector-valued model using Mathematica [closed]

I'm wondering if there is a way within Mathematica to perform some kind of parameter fitting on a vector-valued model function (in this case a model of electric field vectors). Essentially what I want ...
133 views

### How to do linear fit for 2D data points [closed]

I am very much new to Mathematica, and facing several difficulties. I used the following code Fit[{2, 4, 6, 8}, {1, x}, x] The output is ...
122 views

### Computing a Gamma function-Gaussian integral

I would like to compute the following function: Integrate[Gamma[k,0,Exp[-2 e x^2]],x] k is an integer and ...
134 views

### How can I use NonlinearModelFit with multiple variables? [closed]

I am trying to find the coefficients for following equation: $\quad \quad f(x,\,y,\,z) = a (x^2)\, exp(b x + y^2) + c z^2 y$ using NonlinearModelFit. But I can't ...
42 views

### How does LinearModelFit handle cases where the design matrix rank is lower than the model terms?

So, I understand what this error means: ...
287 views

### Interpreting P-Value on ParameterTable

When using LinearModelFit[] we can generate a table of parameter values and statistics for the corresponding model using the property "ParameterTable". Looking in the documentation I can't find an ...
390 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 ...
721 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, ...
295 views

### How to fit parameters in a system of coupled differential equations

Problem description: I'm studying a chemical reaction that can be modeled by a system of coupled differential equations, and I want to use measured data to determine the parameters that appear in the ...
1k 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 ...