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

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5
votes
1answer
99 views

How are p-values in fittings estimated?

I am trying to understand how p-values retrieved in a ParameterTable estimated but I couldn't find any specific information in the documentation about this. For instance, considering ...
1
vote
0answers
62 views

NonlinearModelFit::nrnum error

I'm trying to fit data (including some small negative numbers at both extremes) to a normal distribution. ...
-1
votes
1answer
55 views

Pulling variable out of NonlinearModelFit [on hold]

I have a fit, Dynamic[f1 = NonlinearModelFit[d1, a Exp[-(b (x - c1))^2] + yoff, {a, b}, x]] Where I need to be able to access ...
3
votes
2answers
76 views

Gauss Fit to List of 2D Points

I've been trying to find a solution to what I think is a common problem. I have a list of Data like ...
5
votes
1answer
74 views

FindFormula can't deal with the population data from Wolfram server

In the documentation of FindFormula, the first application of it is to predict the population of Poland. ...
-1
votes
0answers
18 views

How to fit a 3-parameter logistic model by R and GLM [closed]

I have a model follow a 3-parameter logistic model like: $E(Y|x;\beta)=\frac{\beta_2}{1+exp\{(\beta_1-log_2x)/\beta_0\}}$ How can I use GLM to fit this model in R?
0
votes
0answers
49 views

Modify measured values to improve NonlinearModelFit results

Problem: Measured data points have a random distribution of DC offsets (either +/- 0.65 mV), that came from an incorrect setting on the 24-bit ADC we were using. Essentially for each measured voltage ...
2
votes
0answers
96 views

Fitting local regression through data

Is there a way to fit local regression through data in Mathematica (equivalent to say "smooth" in ggplot-R)? I've literally spent the last hour searching the internet and documentation centre and I ...
1
vote
1answer
87 views

Problem fitting when some data is missing

I have a problem fitting a function to data, where I only have the falling and rising edges of the data, with the peak having been capped and was wondering if you have some tips. The data should have ...
27
votes
2answers
435 views

What is behind Mathematica's experimental `FindFormula` function?

In version 10.2 there is a new experimental function: FindFormula. I suspect that a genetic programming algorithm (symbolic regression) is behind this new feature ...
0
votes
0answers
54 views

How to calculate the standard error of a parameter for a simple nonlinear fit?

I am trying to get the standard error of the estimate of a parameter in a simple nonlinear fit. I manage to get it for a linear fit. I used the formulation from a previous post. Here is my code for ...
3
votes
0answers
82 views

How to find the best fit for given input data? [closed]

I have the following data: ...
0
votes
0answers
3 views

Heston Model parameter estimation [migrated]

I would like to know, whether there is some literature or paper (even better) available that examines the Heston model parameter estimation. I am not searching for calibration, it should only focus ...
2
votes
1answer
72 views

Still more problems with Fitting, please help

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 ...
2
votes
3answers
170 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 ...
2
votes
2answers
53 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 ...
2
votes
2answers
57 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 ...
1
vote
1answer
66 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 ...
0
votes
1answer
40 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 ...
3
votes
3answers
272 views

Fitting - Exponential

I'm trying to fit the following data using Mathematica, but unfortunately im not getting any decent results. ...
1
vote
2answers
86 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 ...
1
vote
0answers
85 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 ...
4
votes
1answer
152 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. This data should be periodic with a period of $0.2 \textrm{m}$ and it is the ...
0
votes
0answers
32 views

R^2 values for piecewise regression

So I've used NonlinearModelFit on a Piecewise function and gotten a nice little piecewise regression. This is what my code looks like: ...
-1
votes
1answer
80 views

NonlinearModelFit errors and precision

For this problem, I use a data set, which I've made available here. ...
1
vote
2answers
77 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. ...
1
vote
2answers
65 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 ...
0
votes
0answers
26 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 ...
0
votes
0answers
34 views

Which one will gives best fitting result?

I want to find out the parameters A, B, and C of the ...
2
votes
1answer
86 views
2
votes
1answer
87 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 ...
4
votes
1answer
92 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 ...
0
votes
0answers
54 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 ...
1
vote
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 ...
3
votes
0answers
111 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 ...
2
votes
1answer
97 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: ...
1
vote
1answer
53 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
votes
1answer
89 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 ...
0
votes
2answers
85 views
0
votes
0answers
80 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 ...
1
vote
0answers
35 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 ...
1
vote
1answer
79 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 ...
2
votes
2answers
74 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 ...
5
votes
1answer
211 views

ODE fitting to dataset

So, I have a ODE system, it is a complex biochemical kinetic mechanism with six species changing over time. ...
3
votes
0answers
77 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, ...
0
votes
0answers
49 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 ...
5
votes
1answer
125 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
vote
1answer
95 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 ...
0
votes
0answers
43 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 ...
0
votes
0answers
57 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 ...