Questions on the use of Mathematica to construct models for approximating empirical data. (FindFit[], Fit[], LinearModelFit[], NonlinearModelFit[], etc.)
-1
votes
1answer
177 views
Multivariate Function Approximation With a Large Dataset
I have a nice amount of data from a trading strategy I am working on, where I have two different liquidity parameters as x, y variables.
Before entering a trade I am taking the moving average of ...
10
votes
0answers
134 views
5
votes
0answers
64 views
Using perpendicular offsets in FindFit
I want to use perpendicular offsets in the built-in FindFit function.
Are there any possible ways or do I have to code everything by myself?
5
votes
0answers
194 views
Mathematica vs Sigmaplot (Non LinearModelFit)
I asked a question in a previous post that was closed because "The title of the question is not correct and the issue here is too trivial to help anyone later".
NonLinearModelFit
It's possible ...
5
votes
0answers
228 views
NonlinearModelFit weights
I would like to know how to perform a nonlinear regression on a table with measurement errors. The table consists of two columns, and both have errors. I've been watching some tutorial and it is very ...
4
votes
0answers
458 views
Analytical model fitting
I have a special type of model fitting problem that I am trying to solve in Mathematica. Any insight how to attack it using available tools of Mathematica will be great to hear.
We have a variable
$$
...
3
votes
0answers
154 views
Mathematica Complains about Non Symmetric Covariance matrix, when it's not the case
I was doing some fitting with Mathematica7 using NonlinearModelFit. It's quite long the program to do the fit and that's why I am not displaying here ...
It goes ok, and I can get the fit parameters ...
2
votes
0answers
80 views
Is it possible to marginalize one or several parameters obtained from fitting procedure?
Statistical model analysis package has a few fitting functions. Their arguments are data points, fitting model and parameters in the fit. The result is a set of best values for parameters, which ...
2
votes
0answers
159 views
How to predict some constant number of values with NeuralNetworks
Example:
<< NeuralNetworks`
data = {Sin[#]} & /@ Range[0, 4 Pi, 0.5];
learn = data[[1 ;; 15]];
Now, lets fit our neural network:
...
1
vote
0answers
79 views
Performance in parameter estimation from ParametricNDSolve using varied initial conditions
I have 250 data points from a timecourse exeriment in a list, with columns specifying (1) time, (2-4) initial conditions, (5) absorbance reading. I want to fit 4 parameters (k1, k2, k3, k4) in a DAE ...
1
vote
0answers
55 views
Fitting a set if data to a 'plane'
I have a set of data ({{1,4,2},{1,-1,2},{-1,2,4},{2,1,5},{-1,1,4},{1,1,2},{5,2,2}}) that I am some how supposed to fit to "the plane, that is with the function ...
1
vote
0answers
65 views
Method used by FindFit
Using FindFit, Mathematica selects an optimal algorithm when Automatic is selected.
I'd like to know the name of the method ...
1
vote
0answers
173 views
Methods for NonlinearModelFit
I am using NonlinearModelFit for a thesis project.
I get quite different results if I change the Method to LevenbergMarquardt or QuasiNewton or ConjugateGradient ...
1
vote
0answers
166 views
fit using parametric equations
I have experimental data with two columns (x & y). I need to fit the data to two parametric equations of the form
$$y =\text{const}_1 \times
\left( \frac{\int _a^{b}\sqrt{\frac{\left( 1+\gamma ...
0
votes
0answers
70 views
FindFit and NIntegrate with dependency between integration variables
I am trying to use FindFit and NIntegrate in this situation:
...
0
votes
0answers
130 views
Fitting a theoretical density function with log-return sample
I am working on a exercise to fit a theoretical density
function,presented below, with log-return series of a stock.
$\frac{1}{2}a e^{a(x-\mu)} \quad \text{if x } < \mu $
or
$ ...
0
votes
0answers
87 views
NMinimize::nnum: Question for fitting the data
I'm just wondering if someone could help me solve NMinimize::nnum: problem? I still can't find a solution for it. I used NDSolve to solve my functions. And trying ...
0
votes
0answers
179 views
ParametricNDSolveValue or NDSolve + fitting
I have been trying to find the value for the parameter kestim that yields the best fit of a model to some data points. datac has ...
0
votes
0answers
153 views
NonlinearModelFit:cvmit: Failed to converge to the requested accuracy or Precision within 1000 iterations
I am trying to find some parameters from a model using NonlinearModelFit, but I always get the same error:
NonlinearModelFit:cvmit: Failed to converge to the ...
0
votes
0answers
251 views
Find parameters to fit data with a function
I have a question regarding to find parameters (k1 & k2) to fit functions. At the beginning, I guessed ...
-1
votes
0answers
56 views
Why is NonlinearModelFit calling the model function with symbolic arguments?
I have a model to fit which is made of numerical functions and so it can give a value for any numerical value of the arguments, but creates an error when called with symbols. ...
