FAQ Database Discussion Community


Non-monotonic spline fitting

curve-fitting,data-fitting
I've done a spline interpolation of a 3D path using 2 2D fits. Using the interpolation condition as well as the requirement to be 2 times differentiable I got the required equations to interpolate my 3D path. However I came to realize, that I disregarded the fact, that the paths...

Gnuplot fitting not working well (Unlike KaleidaGraph)

gnuplot,data-fitting
I am currently trying to use gnuplot to fit the a simple data set using the beneath commands, however I am having no luck despite including good initial guesses. Commands: gnuplot> f(x) = 1/(2*pi) * 1/m1 * 1/(b + x**2)**(-3/2) gnuplot> m1 = 150 gnuplot> m2 = 17 gnuplot> fit...

data fitting an ellipse in 3D space

matlab,mathematical-optimization,ellipse,data-fitting
Forum I've got a set of data that apparently forms an ellipse in 3D space (not an ellipsoid, but a curve in 3D). Being inspired by following thread http://au.mathworks.com/matlabcentral/newsreader/view_thread/65773 and with the help from someone ,I manage to get the optimization code running and outputs a set of best parameters...

How to find coefficients for a possible exponential approximation

matlab,octave,curve-fitting,data-fitting
I have data like this: y = [0.001 0.0042222222 0.0074444444 0.0106666667 0.0138888889 0.0171111111 0.0203333333 0.0235555556 0.0267777778 0.03] and x = [3.52E-06 9.72E-05 0.0002822918 0.0004929136 0.0006759156 0.0008199029 0.0009092797 0.0009458332 0.0009749509 0.0009892005] and I want y to be a function of x with y = a(0.01 − b*n^−cx). What is the best...

Fit an integral function with parametric limit to data with Python (Debye Model)

python,python-2.7,python-2.x,integral,data-fitting
I am trying to fit resistivity vs temperature data to Bloch-Gruneisen formula for resistivity in metals: function as you can see there is an integral function with a parametric limit. I don't know how to implement an algorithm to run a least squares fit. I came up with: import matplotlib.pyplot...

gnuplot - get errors on fit parameters, get fit output values as variables, print variable to screen

variables,gnuplot,curve-fitting,data-fitting,function-fitting
Initial Question (Partially Answered) I am using gnuplot's fitting routines to fit a function to some data, and extract a "characteristic decay time constant". (I call this parameter d in my fitting function.) I have used the script code set fit quiet to prevent reams of text being printed to...

Resistivity non linear fit in Python

python,data-fitting,function-fitting
I'm trying to fit Einstein approximation of resistivity in a solid in a set of experimental data. I have resistivity vs temperature (from 200 to 4 K) import xlrd as xd import matplotlib.pyplot as plt import numpy as np import pylab as pl import scipy as sp from scipy.optimize import...

How to fit datasets so that they share some (but not all) parameter values

python,numpy,scipy,curve-fitting,data-fitting
Say I want to fit two arrays x_data_one and y_data_one with an exponential function. In order to do that I might use the following code (in which x_data_one and y_data_one are given dummy definitions): import numpy as np from scipy.optimize import curve_fit def power_law(x, a, b, c): return a *...

Fitting a sum to data in Python

python,scipy,curve-fitting,data-fitting
Given that the fitting function is of type: I intend to fit such function to the experimental data (x,y=f(x)) that I have. But then I have some doubts: How do I define my fitting function when there's a summation involved? Once the function defined, i.e. def func(..) return ... is...