Questions tagged [curve-fitting]
For questions about determining parameters for particular functional form based on set of given data points. These points may be the exact values generated from some underlying function or possibly have some additional noise component.
67 questions
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Curve fitting for oscillating data
This is my first question. I have the following data that I'd like to approximate as a parametric function:
\begin{align}
y = a + (bx_1 + cx_2 + dx_3 + ex_1x_2 + fx_1x_3 + gx_2x_3 + hx_1x_2x_3 + i)*(...
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Fitting with a linear combination of exponentials
I want to elaborate on a statement I read in Acton's "Numerical methods that work", paragraph "Exponential fitting", page 252.
Computationally we are being asked to fit only the parameters $A$ and $...
- 443
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Pseudo Code for non linear power function fit needed
I am struggling finding pseudo Code for a non-linear fit of the following function:
$y = a\, x^b$
Package NLS in R does perform well, but utilizing external software is not practicable in my program ...
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Fit curve with rectangles
I have a one-dimensional set of points, i.e. $(n,y_n), 1\leq n \leq N$. I want to fit them with a linear combination of $k$ rectangular functions in a least-squared-error sense. Each rectangle is ...
- 607
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Question on speed and accuracy comparisons of different 2D curve fitting methods
This may be a trivial question, and I apologize if so. Consider the following simple problem: We have a 2D, regular grid of points (say $X = [0,5000] \times [0,5000]$) spaced uniformly by units of 1 (...
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Problems Implementing the Remez Algorithm
So first off:
*** This code is not being used in production software.
It is a personal project of mine, trying to understand
approximation theory and advanced curve fitting.
In other words, I'm ...
2
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Inverted value is not consistent with expectation
We have a group of observations
$$y = f(x_1, x_2, x_3) \enspace .$$
We have also a forward model $y = f(x_1, x_2)$. The forward model does not include $x_3$ because $x_3$ might include dozens of ...
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1D fit on a surface in matlab
I have a problem fitting a $N\times N$ ($32\times 32$ in this case) matrix in Matlab.
Here is the deal
I have this image, and I want to create 1 dimensional fit between the points and then be able ...
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1
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Curve Fitting problem MATLAB
I have a system of differential equations with some unknown parameters and I need to find the optimal parameter set that fits best with the data I have.
For each parameter set choice (using for loops)...
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Power series regression linear fit in VBA excel
I wrote a program that calculates the best fit in VBA excel for the following model
$$
y_k=c_1x_k+c_0+c_{-1}(x_k)^{-1}
$$
solving for the best fit parameters $c_1$, $c_0$, and $c_{-1}$. However I ...
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How to curve fit an unknown function?
I have data which can be described by $y=f(x,z)$ where $z$ varies from 170 ~ 154. Now values given by $ks$ are known sample values that equals value given in the table header, $uks$ are unknown ...
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Conceptual question about fitting of scattered data
What are the problems that arise when fitting (2D or 3D) a set of scattered data? (non uniformly distributed)
I had some data I had to fit and I solved the problem using the ...
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Piecewise linear approximation of an experimental data curve. Knots position constrained
I need to fit a curve, obtained from experimental data, with a piecewise linear model (4 knots and therefore 3 lines).
I tried using the MATLAB function
...
- 402
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How to connect two fitted B-spline curve?
I use B-spline curve fitting to obtain one smooth curve. If I obtain two smooth B-spline , how can I connect then smoothly. For example, I have 59 points((x0,y0,z0),...,(x58, y58, z58)) and I have two ...
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Number of control points for B-spline curve
I am trying to use B spline curve fitting. The order of B-spline curve is 4. When I have many control points, it works well.
However if the number of control points is small such as two, my program ...
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Produce one smooth curve on one triangle mesh
I hope to get one smooth curve on one triangle mesh. I get one path on the mesh at first. The path consists of vertices of the mesh. I can see the path from the image below.
Each one green dot ...
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Finding self-similar solutions
Is there a general approach to finding self-similar solutions; i.e. collapsing several functions onto a single function by some transformation?
I have data from some experiments, and the functions ...
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