Nonlinear Fitting

Python program for fitting rate constants to primarily kinetic data as 1st or 2nd order kinetics or autocatalysis. It also allows specific noise cancelling, data smoothing by fourrier transform, box averaging and flowing mean. For Python 2.6 or earlier. Platforms: Windows, Mac, Linux

A plug-in for Abaqus FEA with empiric data for many types of materials (linear, nonlinear, ortotropic). A simple GUI for creating properties for common materials and sections for bulk and shells. Platforms: Windows, Mac, Linux

Motofit co-refines Neutron and X-ray reflectometry data, using the Abeles matrix / Parratt recursion and least squares fitting (Genetic algorithm or Levenberg Marquardt). It works in the IGOR Pro environment (TM Wavemetrics). Platforms: Windows, Mac, Linux

Nifty Sim is a high-performance nonlinear finite element solver, developed at University College London. A key feature is the option of GPU-based execution, which allows the solver to significantly out-perform equivalent commercial packages. Platforms: Windows, Mac, Linux

peak-o-mat is a curve fitting program aimed at the fast and easy fitting of spectroscopic data, especially if you face a large amount of similar spectra. Platforms: Windows, Mac, Linux

Lightning Brain ImageHorn for Adobe ® InDesign CS/CS2/CS3/CS4 is a plug-in designed to enable dynamic image fitting ('horn' like in 'shoehorn'). Dynamic image fitting automatically re-applies the selected fitting settings to an image each time you resize the frame that contains it. Platforms: Mac

The state space model is nonlinear and is input to the function along with the current measurement. It performs the extended Kalman filter and returns the estimated next state and error covariance. Requirements: - MATLAB 7.6 or higher Platforms: Windows, Mac, *nix, Matlab, BSD Solaris

The model relies on the theory of strength of least square curve fitting and auto regression techniques. Requirements: - MATLAB 7.5 or higher Platforms: Windows, Mac, *nix, Matlab, BSD Solaris

GMT is an open source collection of ~60 tools for manipulating geographic and Cartesian data sets (including filtering, trend fitting, gridding, projecting, etc.) and producing Encapsulated PostScript File (EPS) illustrations ranging from simple x-y plots via contour maps to artificially... Platforms: *nix, C/C++, BSD

The function plot_hht is a realization of the Hilbert-Huang transform (HHT). The HHT decomposes a signal into intrinsic mode functions (or IMFs), and obtain the instantaneous frequency data. It is designed to work well for data that are nonstationary and nonlinear... Platforms: Matlab

Nonlinearity detection scheme based on zeroing the initial time response over various intervals and computing the FFT of each, as described in: M. S. Allen and R. L. Mayes, "Estimating the Degree of Nonlinearity in Transient Responses with Zeroed Early-Time Fast Fourier Transforms," in... Platforms: Matlab

Although many aspects of a control system can be understood based on linear theory, some nonlinear effects must be accounted for in practically all controllers. Windup is such a phenomena, which is caused by the interaction of integral action and saturations. All actuators have limitations: a... Platforms: Matlab

The forced Duffing oscillator exhibits behavior ranging from limit cycles to chaos due to its nonlinear dynamics. When the periodic force that drives the system is large, chaotic behavior emerges and the phase space diagram is a strange attractor. In that case the behavior of the system is... Platforms: Matlab

zpkfit uses the nonlinear least-squares fitter (lsqnonlin) to fit an analytic model of any (fixed) number of poles and zeroes to numerical (presumably measured) frequency response data. It takes as arguments a frequency vector, a frequency response vector, and vectors of the initial guesses of... Platforms: Matlab

clickfit_OH.m lets you mouse-click a series of datapoints on top of a (noisy) scatterplot and returns a spline or polynomial regression through the clicked dataseries. In addition the clicked series itself is returned.clickfit_OH.m uses an altered version of ginput.m (ginput_OH.m) that from the... Platforms: Matlab

Mean or standard deviation are usually computed for whole part of the analysed signal. However, sometimes we would like to know how this quantities are changing in the data flow. MEANSTDF compute the expected mean and standard deviation values using user defined window for every data position.... Platforms: Matlab

Some curve fitting or smoothing tools can benefit from knowledge of the noise variance to expect on your data. Kalman filters use this information, also some spline fitting tools. So I wrote a function to extract the noise variance from a signal vector. It also works on any specified dimension of... Platforms: Matlab

This is an accelerated PSO (APSO), developed by Xin-She Yang in 2008. APSO does not use velocities or any inertia parameter.A full program for solving nonlinear constrained optimization problem (welded beam design as an example) is provided, which can be extended to solve other continuous... Platforms: Matlab

This is a nonlinear system of differential and algebriac equations, that describe the dynamics of a continuous bioreactor. The bioreactor simulates the production of ethanol through yeast fermentation. The model is described in:Z. K. Nagy, Model Based Control of a Fermentation Bioreactor using... Platforms: Matlab

The program determines the constants Rmax and Km of the Michaelis-Menten model using data given in Fundamentals of Chemical Reaction Engineering by M. E. Davis & R. J. Davis, McGraw Hill, 2003. This data represents the substrate (catechol) concentration versus time. This data was obtained using... Platforms: Matlab