# Questions tagged [fitting]

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

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### Fittings of three equations

Can you help me to do the fit for the following equations to obtain the values of $a$ and $b$. {20.7 == a + b/(5^4), 28.62 == a + b/(6^4), 32.04 == a + b/(7^4)} ...
69 views

### Solving ODE System and Estimating Parameters with Experimental Data

I am new to Mathematica. I am trying to find out the best-fit values of the parameters appearing in an ODE system of three equations. The three ODE equations are: ...
76 views

### Is it feasible to curve fit to a staircase function? [closed]

Taking as a starting point the advice given in this post I am trying to fit data to a staircase function as follows: ...
104 views

### Mathematica slow at estimating vector autoregressive model parameters

I have been trying to obtain VAR model parameters using EstimatedProcess and FindProcessParameters. It seems to take a very long time as soon as I have more than 6 or 7 time series and lag length >2. ...
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### How can I get the standard error of parameters from FindFit?

I used FindFit with Norm function as written below. ...
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### How to perform a 2D-multi-peak fitting?

I am wondering how to decompose the data[x,y] into several elliptic-shaped functions, i.e. $f[x,y]=\frac{H}{(1+(\frac{x-x1}{a1})^2+(\frac{y-y1}{b1})^2)^{3/2}}$. I could follow in 1D case, ...
101 views

### What does “Solved to an acceptable level” mean in the context of NonlinearModelFit in M12

I made a simple cosine fit to some data: ...
167 views

### How to merge two or more curves smoothly?

I have plotted three curves. For each range of $x$, one of those curves is true. On the other hand, finally, the result must be a unified curve. Is there any command to unify these three curves? ...
67 views

### Fitting different data sets with different models and 2 free variables using FindFit

I have a T1 equation from which I got two noisy datasets, one for y=0 (datax) and the other for x=0 (datay) (t is always equal to 1): ...
51 views

### Fit piecewise function

I want to fit my data with the following function ...
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### Approximating missing data points in a list using fit models [closed]

Suppose I have the following list: l={0, 76, 413, 942, 1344, 1651, 1486, 1013, 581, 237, 65, 17, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} I want to find a fit ...
42 views

### Get R^2 value between interpolating functions and a list of points

I am looking to compare the degree of accuracy of a theoretical model by comparing my theoretical curve to my experimental data points. My theoretical curve is an interpolating function generated ...
68 views

### How to fit a spline (not interpolate) through points in 3D?

I have coordinates of points in 3D and want to fit a spline through these points. I found a least square approach for 2D case: https://demonstrations.wolfram.com/...
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### NonlinearModelFit won't fit to gaussian data

The form I'm using should be correct because when I input my initial guesses it plots a shape similar to my data. When I use NonlinearModelFit, the fit is not correct at all and is almost flat, then ...
44 views

### FindFormula: can I change the standard TargetFunctions?

FindFormula seems to have a limited number of TargetFunctions: Possible functions for TargetFunctions are Plus, Times, Power, Sin, Cos, Tan, Cot, Log, Sqrt, Csc, Sec, Abs, and Exp. Is it ...
147 views

### How to fit spline through points in $\mathbb{R}^3$?

I have coordinates of points that represent a curve (for example, helix or centerline of moebius strip) in $\mathbb{R^3}$. I want to fit a Bspline through these points. How to do this in Mathematica? ...
214 views

### Linear fitting without intercept

I want to fit the following model: $y_t=\beta x_t+\epsilon_t$ For that, I've tried the following ...
44 views

### How to add constraints to “Fitting unknown number of Gaussians to data”?

This question of how to fit a sum Gaussians, where the number of Gaussians is to be determined, to data is answered nicely already by Fittting data with combination of an unknown number of Gaussians, ...
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### A curve fitting by two Lorentz function

I am trying to fit my curve by two Lorentzian functions but i could not fit it properly, i found a lot of examples about Lorentzian fitting but none of this work with my data. Here is my code what i ...
43 views

### How to find the Maximal Absolute Error?

I found this fit but I do not understand how to find the maximal absolute error nor do I understand what it is really. I do not see what it is I would compare, would it be ...
I have data of a function that goes like $f(x)\propto x ^\alpha$ for a certain range of $x$ and like $f(x)\propto x^\beta$ for another one. It is common in the literature to make a log log plot and ...