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

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48 views

Fitting 6 differential equations to 6 sets of data

I am using the newest Mathematica and I am trying to fit a set of 6 linear differential equations to a set of experimental data for each of the six variables. I am a baby beginner at this and could ...
5
votes
1answer
213 views

Modeling of soccer results using GeneralizedLinearModelFit

I am trying to recreate the regression in "Analysis of sports data by using bivariate Poisson models," which can be found here, http://tolstoy.newcastle.edu.au/R/e8/help/att-6544/karlisntzuofras03.pdf....
0
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2answers
92 views

Find min-max for slope in linear fit

I have a following data which follows a linear model with intercept zero, i.e. $$y = mx $$ ...
1
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2answers
88 views

List argument for NonlinearModelFit

If I have a function of list argument (presumably with large number of entries), how can I pass it to NonlinearModelFit? I don't want to pass it by pattern checking ...
0
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0answers
44 views

Finding error in an exponential fit

I'm a beginner with Mathematica and I'm trying to find the error in 'A' from the following fit: -A I0 E^(-Y A) The code I've used to plot the fit is the ...
0
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0answers
64 views

Exact meaning of `VarianceEstimatorFunction`

After reading the documentation, it's still unclear for me what VarianceEstimatorFunction does when fed with two arguments: ...
1
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0answers
35 views

Fitting Data when both Variables Have Uncertainties [duplicate]

Does there exist a method in Mathematica for fitting some function f(x; a, b)=y (with parameters a, b) to data of the form {x, y} when both x and y have different uncertainties? It seems like it would ...
0
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2answers
119 views

A case of complicated fitting of multiple datasets

I've stumbled upon a difficulty while trying to do some fitting which may be called sorta complicated. I'll try to introduce my problem step by step. To begin with, I have a number of datasets ...
1
vote
1answer
89 views

Sum to Zero Constraint in GeneralizedLinearModelFit

Is there a way to impose a constraint on a generalized linear model fit in Mathematica? In R, when using the glm() function, you can set options(contrasts=c('YY.sum', 'ZZ.sum')). Is there something ...
0
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1answer
96 views

How to Find minimum and maximum using `FindMaximum[]` and `FindMinimum[]`

this is the data that i use to plot. data_damped_osccilation this is my code so far, however it still give me error ...
0
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2answers
63 views

NonLinearModelFitting constant offset problem

I have written the following code: ...
1
vote
1answer
112 views

Standard error of linear fit parameters

I fitted data belonging to a MSD (mean squared displacement of a vibrating micrometer sized particle) by using a linear function: ...
0
votes
1answer
49 views

Failed to extract parameters by fitting data with ODE

I'm trying to extract 4 parameters by fitting one set of data with an ODE via NonlinearModelFit. I originally thought the process should be straightforward, but later on I found I was totally wrong. ...
3
votes
2answers
221 views

Is there is a decreasing function that fits my data?

Cross-posted in http://tieba.baidu.com/p/4440556337 http://tieba.baidu.com/p/4440547130 I was wondering if there is a function that fits the following data perfectly or properly. There is a ...
0
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1answer
39 views

NonlinearModelFit for analytical data is giving errors [closed]

"x is lambda, y is alpha, z is the factor of pressure" ...
0
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0answers
44 views

fit multiple dataset with a single ODE to extract parameters

I found my problem very similar to the one discussed in here. But I'm having difficulties to fit multiple dataset (with varied temperatures) to a single ODE. The hurdle for me now is since the rate ...
3
votes
2answers
255 views

Why can't FindFit get the proper result in this problem?

Cross-posted in http://tieba.baidu.com/p/4425634583 The mathematica helps me solve one differential equation in numerial method and got the data of the answer,but the taylor series fit is not good in ...
0
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0answers
78 views

Maximum Likelihood Estimation of Gamma-distribution Scale parameter

I have the following tasks: Generate random sample with given parameters shape = 2, scale = 0.001 and shape = 2, scale = 1/1200 for the right censored sample; Using Maximum Likelihood Method ...
0
votes
1answer
62 views

FindFit only fitting portions of data

I'm currently trying to fit some complicated data sets and I am having some luck. The higher temperature data works just fine with FindFit. Unfortunately, however,...
0
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0answers
44 views

Plotting error bars in both dimensions for straight line model [duplicate]

I want to fit a straight line model of the form $y_i = a+ b\ x_i$ to the list of $(x, y)$ pairs given below. How can I plot the data with error bars in both coordinates? ...
2
votes
1answer
85 views

Fitting EV charging curve

I would like to fit my set of data (x = time and y = power) as seen below, and obtain function of x describing it as close as possible, in order to manipulate it (applying different SOC, time offsets ...
0
votes
2answers
59 views

Plotting plane from a matrix or data table

After weeks collecting data I've decided to pass my results through Wolfram Alpha and see what it gets. The results are amazingly useful, specially the plane generated by linear regression. It is ...
13
votes
5answers
2k views

Fit image of mountain to gaussian

I want to detect the edges of an image of a mountain and then fit that to a gaussian. I am unsure about how to only get the mountain edge, rather than every single edge in the image. How do I ...
1
vote
2answers
72 views

Putting suitable constraints on the `Find` family of functions

Can any of the Find group of functions be used to get a good curve-fit for a range of data, if the value of $f(1)$ is known, and the value of $\lim_{n\rightarrow \...
2
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0answers
61 views

Algorithm used by Fit[]

Does anyone know what algorithm Mathematica's basic Fit[] function uses? Is it proprietary? I'm trying to do some pretty basic, linear, polynomial data fitting (...
-2
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1answer
99 views

Computing least squares error [closed]

I have a mathematica subroutine setup that computes the least squares approximation as follows ...
4
votes
4answers
193 views

Fitting Coxian distribution to some data

I'm trying to fit a transformed (actually shifted to the right) Coxian distribution to some data ( if needed an example set is here Sim data ). I've tried a number of ways for this: ...
5
votes
0answers
103 views

Ridge and lasso regression missing? [closed]

There is no implemented command to perform ridge or lasso regression? I couldn't find it in the documentation. Might be there are add-on packages I am not aware of.
3
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0answers
98 views

Writing a function to set up and solve the least squares problem

I have setup the explicit line equation for a given set of points using least-squares approximation and the knots computed below. I have tried extending the same code for use with an arbitrary degree, ...
1
vote
2answers
143 views

Problem fitting a exponential function to data points [closed]

finale edit: i found someone who solved my problem via matlab. therefore i wont try out the proposed solutions now, but wont delete my question in case someone might have use for the proposed ...
1
vote
0answers
49 views

NonLinearModelFit to a Function [closed]

I have a multiple dimension function that is fairly complicated. Instead of simply using Series to get a taylor series of the function, I would rather specify my ...
3
votes
2answers
178 views

Low quality of estimated parameters with NonlinearModelFit

I'm trying to fit formula: ...
5
votes
1answer
107 views

Why is NonlinearModelFit not working?

I have a set of x,y-values ...
1
vote
1answer
75 views

Faster way to test possible points-to-plane-fitting identity?

Summary: I want to confirm the three sum-defined quantities in https://github.com/barrycarter/bcapps/blob/master/STACK/planetest.m (also below) are identically zero for all values of n>=3. While ...
1
vote
0answers
94 views

LinearModelFit: Standard error or Standard error of the mean on the slope [closed]

UPDATED 02/14/16 Let me make this question clearer. Suppose each measurement that I make consists of three points, each with its own error governed by a normal distribution, on an XY plot. Obviously ...
1
vote
1answer
111 views

LinearModelFit: How to compute R-squared? [closed]

Is there a simple way to computed the R-Squared(adjusted and not adjusted), from the LinearModelFit? It has so many options, but none for the R-Squared, that I suspect there's a simple way to compute ...
1
vote
1answer
84 views

Fitting bivariate data using FindFit [closed]

I am trying to fit the following bivariate data set using the FindFit function: ...
3
votes
2answers
67 views

Problem with FindFit: Low quality of estimated parameters

I'm trying to fit a Cole-Davidson formula: ...
9
votes
3answers
184 views

Linear fit with conditional noise distribution

I need to fit a linear model of the form $y_i = a · x_i + b + e_i$. The $e_i$ are independent noise from a distribution that depends on $x$ as well as on global parameters of the data; however, the ...
2
votes
1answer
130 views

Find a family of curves

I have a diagram with seven curves (each with a different parameter). My goal is to find a function for the family of curves (i.e. a single function not just for the seven parameters, but for all ...
0
votes
1answer
80 views

How can I calculate the root of any order of power series

How can I calculate the root of any order of power series with Mathematica. Here I insert every quantity by hand. But I want to give a, ...
1
vote
0answers
79 views

x and y axis nonlinear error fit possible? [duplicate]

I have a set of datapoints with x (position) errors as well as y (measurement) errors. Is there a way in Mathematica to fit a nonlinear function through this points, with weighting both, the x and y ...
24
votes
3answers
836 views

Exponential fitting - isn't actually a BUG there?

There are many questions on this site about wrong exponential fitting in Mathematica but no one considers this well-known problem as a potential bug. Usually people suggest well-known workarounds ...
6
votes
1answer
326 views

Findfit does not find the best fit

I am working on a project that needs curve fitting. The experimental data should be fitted with a model that calculated with an integration equation. At first, I enter my experimental data ...
0
votes
1answer
95 views

How to fit parameters, not functions?

Given a set of parameters ...
2
votes
0answers
69 views

How to realize Global Fitting with shared parameters, same as OriginPro9.0? [closed]

I have an experimental data from Michelson interference and I can fit the envelope in OriginPro9.0 using Global Fitting with shared parameters. The figure by OriginPro9.0 is like this: However, I ...
1
vote
1answer
75 views

Paramter Scans and $\chi^2$ Test in Mathematica

Is there any in-built function or a recommended package that enables one to find, say, 10 Parameters, which are used as boundary conditions in NDSolve, that minimize $\chi^2$? ...
13
votes
2answers
494 views

Fitting a curve to an image object: not a superellipse, not an egg curve.. what else?

I'm facing the problem of quantifying the morphology of objects with such a shape (nannoconids... they are fossils). One of the final goals is to produce a solid of revolution and compute volume/...
0
votes
2answers
93 views

Getting image data values with coordinates in circular region

I have a number of gray level images (600, with size: 2400x2400 pixel, small instance see above). In this image there is a circular region of interest. The aim is to fit a function to the gray value ...
2
votes
1answer
74 views

Fitting data in Log-Log scale

I want to fit my data from a txt file to a curve in log-log scale. What I tried to do was this: ...