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

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2
votes
2answers
98 views

How to do dynamic range selection for data fitting in Log plot?

In linear plot, this can be achived by Locator like this: http://mathematica.stackexchange.com/a/24935/13580 ...
1
vote
0answers
82 views

How to control precision of parameters in NonlinearModelFit?

I am using NonlinearModelFit for fitting a dataset to some complex numerical model function that depends on a few parameters. The final required precision of these parameters is very low, like 3 ...
0
votes
1answer
49 views

ANOVA on data with different lengths

I have data in the following form: ...
2
votes
0answers
56 views

Kalman filter estimation

Does anyone have any examples of the estimation of Kalman filters in Mathematica? I am new to these filters and struggling to compose the likelihood function. Some examples would be really helpful. ...
1
vote
2answers
95 views

Does FindFit use symbolic differentiation?

Does FindFit use symbolic differentiation when optimizing by least squares a non-linear function?
3
votes
2answers
187 views

FindFit “is not a real number” error when fitting a parametric function to the data

I am using Mathematica's FindFit function to fit a parametric solution to my data and I am getting the error ...
2
votes
2answers
185 views

RSquared: LinearModelFit vs NonlinearModelFit

I'm trying to understand the differences between LinearModelFit and NonlinearModelFit. One thing I notice is that the computation of AdjustedRSquared seems to be different, even when the model results ...
0
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0answers
49 views

NonlinearModelFit not hunting for good values

I have the following data which come from complex values but I have turned them into a 3D list ...
10
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0answers
149 views

How can the Theil-Sen estimator be made to work on larger datasets?

The Theil-Sen estimator finds the slope and intercept of a line passing through a set of points by calculating the median slope and median intercept of the set of lines passing through all possible ...
4
votes
2answers
193 views

Unable to fit function convolved with NIntegrate with FindFit even with NumericQ

I am attempting to fit to the convolution of a simple function with a Gaussian. (I realize this could be done with Convolve also, but I thought I could make it go faster this way). I am able to ...
5
votes
1answer
207 views

Is there any strategy to have a compiled version of FindFit or NonlinearModelFit?

Disclaimer: This is not a precise question with a definite answer. I know that neither FindFit nor NonlinearModelFit is in the ...
0
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0answers
45 views

How do I add custom deviation when using LinearModelFit?

I have a set of data in the form a list S1={{x,y},{x,y}} etc. I also have a function that calculates a corrected standard deviation in the y direction for ...
1
vote
1answer
192 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
80 views

Expand a fitting using FindFit[]

I need to implement multidimensional optimization using FindFit[]. But it's essential to exclude some parameters from the main procedure of optimization and to move on from direct optimization in ...
1
vote
1answer
60 views

Fitting with roots of trascendental equation

I'm new to this community and my first question probably reflect my lack of confidence with Mathematica. My problem is the following: I find the roots of a trascendental equation dependent on a ...
0
votes
1answer
94 views

LinearModelFit - Number of unique basis functions & Invalid variable errors

I'm having trouble with a simple linear fit model. Here is my code ...
0
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0answers
145 views

Extracting parameters from a fitted function

Let's say I have written a function which performs convolution and returns value calculated for the time чtч. ...
1
vote
1answer
126 views

Fitting an imported .txt data

I have some data in a .txt file, and I'm trying to import it to Mathematica and fit it with a function. The data is a 647x647 matrix of values. This seems like it ...
0
votes
2answers
115 views

How to fit points in a picture using locators

I've got a problem doing some analysis work on some of my spectra. I am basically looking for features that look like parabolas. In need of a tool to quickly find two parabolas in a spectrum (they are ...
3
votes
1answer
112 views

How to make a diagnostic plot for the regression?

Context I am interested in LinearModelFit, and would like to make diagnostic plots using Mathematica. I cannot find them in Mathematica document center. For example, the following R program makes ...
1
vote
0answers
113 views

How well does my function fit data? [duplicate]

Oleksandr Karsten suggested me to mark the difference between this question and the one that is already answered: in the other question it is calculated a ...
0
votes
1answer
140 views

NonlinearModelFit - “Encountered a gradient that is effectively zero”, all variables are 1, 1, 1 [duplicate]

I have data of the form {149.45, 0.371093}, {149.362, 0.375976}, {149.277, 0.380858}, ... }, where each element of the list is {x, y}. The plot of this, using ListPlot, gives an approximate Gaussian. ...
3
votes
1answer
78 views

Ordinary Least Squares (OLS) with RLink

I need to calculate the parameters b0, b1 and b2 in: ...
0
votes
1answer
79 views

Binomial Regression where n > 1

I am not well versed in Generalized Linear Models, but am trying to use this approach to model some discrete data. I have binomial data where the sample size for each observation is the same size, ...
0
votes
1answer
67 views

Regression with 3 variables

I'm trying to find a function starting from its values but I can't find anything related to functions with 2 variables and I don't know how to go on. So, given this sample data, I'd like to know how ...
0
votes
1answer
59 views

How to fit this data to be used in NIntegrate later?

I have a list of data points that resemble a chi-squared distribution (long tailed gaussian) that I am having trouble fitting or finding an equation with. The goal is to use the fitted equation in an ...
1
vote
1answer
119 views

FindFit::nrlnum: error with FindFit

I am trying to write a code to fit actual data of the orbit of a star with Mathematica 8. First I tried to write a code to fit a mock orbit, using the Application with differential equations (the ...
3
votes
1answer
228 views

Test Goodness of fit for FindFit

Is there any way to get an estimate of the goodness of fit from FindFit, for instance getting the final error? The documentation doesn't provide any hints, and a quick Google search didn't return any ...
2
votes
2answers
113 views

FindFit working with Integrate but not NIntegrate - I am using “?NumericQ”

I'm having some syntax problems with finding a fit to an equation that doesn't have an analytical expression for it's integral. Because I think the problem is one of syntax, I am substituting a ...
2
votes
0answers
54 views

Is there a way to produce a FittedModel object as the solution to a regularized regression?

I can get the Ridge or Tikhonov regression solution to Y = \[Beta].X easily enough as ...
10
votes
0answers
216 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 ...
1
vote
0answers
105 views

Fitting curves with NonLinearModelFit not working with charge and discharge like data

I'm trying to get a reasonable fit out of mathematica, but i'm not very practical with it. I'm not that good with mathematica at all actually(like cleaniness of the code...). btw, here's my problem: ...
0
votes
0answers
46 views

Troubles with FindFit for ODE (elaboration)

I have asked a question Troubles with FindFit for ODE and get a good-working answer from @belisarius. Nevertheless I need to clarify is it possible to define the same model with ...
2
votes
1answer
108 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 ...
2
votes
1answer
129 views

How do I find out what a Mathematica function is doing (which numerical method it uses and how)?

Long story short, I am working on a project which entails fixing a bug I have found in Mathematica (8 and 10). In general, I would like to know what a specific Mathematica function is actually doing ...
1
vote
1answer
87 views

“Power series” in Cos[n*x] for X coordinate of planetary ellipse

Consider the functions below: ...
1
vote
2answers
216 views

How to obtain the best possible NonlinearFit

Here is some sample data ...
4
votes
1answer
158 views

Find GeometricTransform from 3D object external surfaces to a positional point cloud data

I am looking for another way to approach this problem. Any suggestion on how to optimize the computing speed is welcome. I have a BSplineFunction which accurately ...
1
vote
1answer
116 views

Mixture coefficients and Parameter estimation for moving Normal distributions

I am searching for a way to do the following steps below. I am stumped and I have stumped a few profs too. Any help would be appreciated. I would like to import data from, say, excel or a .txt file ...
0
votes
2answers
66 views

Handling msg for fitting

I have a trivial question: I do Monte Carlo with some curve fitting. Now always when a random run creates a complex fitting solution it should write 1 in a Matrix. How can I handle such msgs in a ...
0
votes
1answer
43 views

Fit inside a module [closed]

I have here a MMA NB which works fine outside the MODULE. BUt in the module routine there comes up an warning that the solution is not real. Can anyone here help please? ...
4
votes
1answer
106 views

Mystifying failure of NonlinearModelFit

Fitting the following two time-series (two repeats of the same exponential growth process) ...
3
votes
1answer
134 views

Troubles with FindFit for ODE

I need to use FindFit for ODE with arbitary number of parameters. This code (from documentation) works: ...
0
votes
1answer
97 views

Fitting data with inclusion of constraints

How do I find a fit for the dataS (see below) with the constraint that the parameter np is an integer, and that the parameters la+lc = 100. A weak attempt at this is provided below for a specific ...
16
votes
2answers
570 views

Curve fitting by running through hundreds of models and return the one with best fit

In the past, I used to solve a lot of my regression analysis (curve fitting) problems with a program called DataFit which runs on Windows. It has hundreds of regression models which it runs through in ...
1
vote
1answer
216 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 ...
5
votes
1answer
209 views

Forcing NonLinearModelFit through a point

Like the title says, is there a way to make an NLM fit pass through a specific point.
0
votes
0answers
51 views

Using List/Histogram Data As A Weighted Function?

I have a list of data points that I would like to use as a weighted fucntion. The data represents the number of particles within a bin of a particle distribution. Ultimately I would like to multiply ...
0
votes
0answers
111 views

Non linear curve fit

I am trying to fit a non linear curve to my data which looks like following The code I am using is following. You can see I have six unknown variables ...
2
votes
1answer
60 views

Is there a way to show some “weighted” residuals after LinearModelFit?

I am fitting some functions to some data and then I want to analyze the residuals of that fit. I'd like to see how those residuals compare to the values of the original data, hence my "weighted" in ...