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

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Why does my Dynamic NonliearModelFit keep running?

I have complex data and which I am fitting to a complex formula. In order to use NonlinearModelFit I split the formula and the data into real and imaginary parts. As usual NonlinearModelFit is ...
5
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3answers
178 views

Finding exponential model from data [duplicate]

I'm trying to find an exponential model from data for a homework problem. There is an accompanying video explaining how to do the bigger problem but it omits any instructions on the step where the ...
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79 views

Defining a Gaussian Distribution Fit to data

I am given a set of data and told ahead of time that the data will need to be fitted to a Gaussian Distribution. I know that Mathematica has preset functions for linear, quadratic, and cubic fits, but ...
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1answer
90 views

General F statistic and p value in LinearModelFit

Many statistical packages provide a "F statistic" and the corresponding p value in their output of a multiple linear regression. I don't find that in the parameters of the Mathematica function ...
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1answer
69 views

Fitting composed model to experimental data

I have mathematical model based on equation: $y(x) = 1 - \sum_{b=1}^{\inf} 2c_b \sin(c_b x/L) \exp(ax) $ (1), where $c_b$ are the positive roots of equation: $c_b \cot c_b + aL = 0$ (2). $L$ is a ...
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1answer
113 views

Using Manipulate to dynamically correct the baseline of a signal

i have data with a baseline and will correct it with a polynomial fit using Manipulate to see immediatly the changes in the resulting spectrum. It works so far, but ...
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0answers
50 views

Stuck in local minimum in NonlinearModelFit using Simulated Annealing?

I recorded a set of experimental rates $r = r(c,T,P)$ at 2 values of $c$ and >15 values of $T$. $r(c,T,P)$ obeys the following functional form: $$ r(c,T,P) = ...
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1answer
133 views

Fitting numerical model to experimental data

I have diffusion equation with the initial/boundary conditions: ...
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31 views

NonlinearModelFit::nrlnum error using FindFit /NonlinearModelFit

My question is related to my previous post I'm trying to fit experimental data (after suggestion here by David) with Airy type function `data01 = Import["366.0000cm_660.0000nm.png"]; data02 = ...
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0answers
92 views

Power::infy: error using FindFit

I have a 2D data to fit (the Airy type pattern from diffraction of Gaussian beam on the circular aperture). Please see the attached picture. I was going to use a function like ...
3
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1answer
109 views

FindFit with parameters which are simultaneously in initial conditions

I have RLC circuit. I would like to find R and L by using FindFit, but L is in initial condition and I have problem with it. Could you help me ? ...
2
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1answer
75 views

Non-linear curve fitting with multiple parameters and conditional expression

The above integral(Bloch Gruneissen formula) is what i like to fit with my experimental data.I am new to Mathematica. To cross-check the fit results obtained in other software, I try to fit with my ...
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1answer
80 views

Formatting and inserting a parameter table into a plot

I'm fitting data, and I want to put the parameter table generated by NoninearModelFit into the plot. How can I do that in a reasonable way? I want to format the ...
4
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1answer
109 views

Removing Linear drift from an oscillating data

I have an array of 800,000 data measured at 1.1s time gap. It is oscillating data but has clear linear drift. I want to remove this linear drift. But the estimates by ...
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0answers
43 views

Cross-validation of a FittedModel

Although I would know how to perform cross-validation tests after fitting a model using a function like NonLinearModelFit, I wonder if there is a way to do this providing the right parameters to the ...
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0answers
95 views

Memory problem in Mathematica 10

I'm having a problem with memory. I'm doing nonliner fits of several data lists to a system of differential equations. When I evaluate the "Do" cycle the memory grows with the iteration step up to my ...
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0answers
33 views

How to fit data with numerical solution of system of parametric ODE? [duplicate]

I need to find the parameters (k1,k2,k3,k4,k1r,k2r,k3r,k4r) that fit my data (list of [Intensity, time]) using the function ...
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1answer
51 views

Can I use boolean parameters in LogitModelFit?

For example, to use 1 as True and 0 as False: ...
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0answers
62 views

Fit convoluted Gaussian and Lorentzian functions to a peak profile

Thanks in advance for anyone who read this. I have a peak profile data like this: ...
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4answers
522 views

What is the natural way of using Dataset to get a FittedModel?

The new Dataset in Mathematica 10 is a great addition to the language, potentially reducing the convenience gap with R. Given this, I would like to understand what the equivalent simple or natural ...
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0answers
96 views

Developing easy code to apply Delta Method to generate prediction bands for custom distributions

I think that this is an interesting issue for all those who when to not only adjust one prediction function, but also to obtain the prediction bands to asses the graphical or tabular error I'm trying ...
3
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3answers
156 views

Zero-order interpolation not going fully around

Connected to this question, I want to do a zero-order interpolation of a bunch of datapoints which is periodic. The code I use is as follows: ...
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1answer
62 views
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1answer
100 views

Making a fit to my empirical data [closed]

I want of plot the fit for the graph The Data for this graph is ...
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0answers
54 views

No real number fitting double exponential in Mathematica

I am trying to fit a double exponential curve to my data, but I got the error saying there are non real number. Also I tried with starting values for my 4 parameters, but this does not work either. ...
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3answers
116 views

Plot least squares curve on Linear Log Plot

I have the following Data: ...
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0answers
44 views

Why do EstimatedDistribution and DistributionFitTest work this way

I am fitting some time-series data to both a stable distribution and a normal distribution in order to assess the goodness of fit of each. Along the way I encountered the following confusing result. ...
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3answers
146 views

Fitting the Plot by fourier Series of either sine or cosine

I have list of data and its plot and I don't know how to fit the plot with fourier series of either sine or cosine. Full Data: ...
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1answer
45 views

What is the definition of FitResiduals

What is the definition of FitResiduals in Mathematica? I could not find its definition in the Mathematica help. Is it the same as chi squared?
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66 views

Logarithmic curve fit in data

I have the following data which are the theoretical: ...
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2answers
234 views

Does FindFit support complex numbers or doesn't it?

Inspired by this previous question: Findfit doesn't give the good fit; Changing the starting values will not change the results. Consider the following complex-valued dataset. ...
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3answers
192 views
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3answers
150 views

Why does FindFit seem to have trouble fitting exponential data?

I have 4 data points. t is in minutes, and y is radioactive counts per minute. When I input the following lines: ...
5
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0answers
200 views

Problems extending NelderMeadMinimize into 2D

Update The eventual route I followed was to adapt a version of the NM-simplex written in C and link to it with MathLink. Once I've tested this out fully I'll post it here. I've been playing around ...
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1answer
102 views

Fitting data to a Poisson distribution

I'm trying to fit a Poisson Distribution to data produced in a lab. I've successfully made a Histogram of the data, which looks like: However, when I try to fit the Poisson Distribution using: ...
2
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1answer
68 views

Piecewise conditions with a parametric PDE

I'm using ParametricNDsolve to check best fit of a model (function Eb1) with some data, and I have four free parameters I want to test. I can easily construct a Parametric solution between the two ...
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2answers
55 views

FindFit is producing a list of imaginary numbers when there is non

I am trying to find the fit of an equation to some data and mathematica thinks there is a list of imaginary values. My data is all real positive number. ...
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0answers
69 views

Horizontal shift in fitting data by a sinusoidal nonlinear model

I have data that can apparently be fitted by a sinusoidal function in form $D+A\sin(B(x-\frac CB))$. I tried doing the best fit in Mathematica using ...
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2answers
115 views

Error function fit of data

I have this experimental data set which I know should follow the Complementary error function. My goal is to find the σ of the associated gaussian distribution. However, I cannot seem to do it in ...
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3answers
202 views

To obtain an equation for a given curve

I have obtained the graph, I would like to know its equation. The graph seems to be a hyperbolic spiral which, its equation reads, $r = a/\theta$. I read here and also, but these are concerning the ...
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0answers
38 views

How do I constrain the result of fitting my non-linear model to be greater then 0

fitresulty21 = NonlinearModelFit[ydata21, {funfit[y, σ, A, B, x1, d, d/2], A > 0}, {{x1, 20}, {σ, 3}, {A, 200}, {B, 2000}, {d, 110}}, y]; ...
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2answers
190 views
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34 views

Fix Parameters for NonLinearModelFit?

Is it possible to fix the parameters for NonLinearModelFit within the function itself instead of defining the fix parameters at the beginning of the notebook? I am ...
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1answer
215 views

Obtaining the envelope of an oscillating function and perform fitting

There is an elegant way to obtain the envelope of an oscillation function explained here http://mathematica.stackexchange.com/a/27854/15966 My question is how to modify the code below so I can fit ...
3
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2answers
204 views

In a ListPlot of LinearModelFit, plot error band

This is similar to this question. The fitted line can be plotted alongside with the data with this code: Show[ListPlot[data], Plot[lm[x], {x, 0, 5}]] I would ...
2
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1answer
58 views

Trouble with using a log10 function in NonlinearModelFit

I was wondering why won't mathematica give a result where the function is also Log10, instead it gives the ordinary Log. Is it ...
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0answers
36 views

A more efficient way of fitting a non-linear model that returns an entire list?

I have a function that takes two parameters, del and nu, and returns a list npoints long ...
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1answer
85 views

Find polynomial equation for set of 3D data

data was given in columns in the order {y, x, z}, with y dependent on x, z ...
0
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1answer
91 views

How do I fit NDSolve result to experimental data? [duplicate]

I have two coupled ordinary differential equations which I solve numerically in Mathematica, but now I want to fit the solution with experimental data. I do following, (the experimental data ...
0
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0answers
32 views

Data Fitting with xerrors and yerrors using findfit [duplicate]

I'm trying to fit data with xerror and yerror using "Findfit", so i'm trying the same form than in tuto : ...