#Error calculation fityk how to

#Error calculation fityk how to

How to read this manual After this introduction, you may read the Chapter 2, Getting started. You can download the latest version of fityk from or To contact the author, visit the same page. Fityk is free software you can redistribute and modify it under the terms of the GPL, version 2. the width of a peak can be an independent variable, the same as the width of another peak, or can be given by complex (and general for all peaks) formula. The main advantage of the program is flexibility - parameters of peaks can be arbitrarily bound to each other, e.g. Fityk offers various nonlinear fitting methods, simple background subtraction and other manipulations to the dataset, easy placement of peaks and changing of peak parameters, support for analysis of series of datasets, automation of common tasks with scripts, and much more. Although the author has a general understanding only of experimental methods other than powder diffraction, he would like to make it useful to as many people as possible. It is reportedly used in crystallography, chromatography, photoluminescence and photoelectron spectroscopy, infrared and Raman spectroscopy, to name but a few. There are also people using it to remove the baseline from data, or to display data only.

The most concise description: peak fitting software. Introduction What is the program for? Fityk is a program for nonlinear fitting of analytical functions (especially peak-shaped) to data (usually experimental data). About this manual Bibliography ivģ Chapter 1. 9 Sum of fitted functions Sum - Introduction Variables Function types and functions User-defined functions (UDF) Speed of computations Sum, F and Z Guessing peak location Displaying information Fitting Nonlinear optimization Fitting related commands Levenberg-Marquardt Nelder-Mead downhill simplex method Genetic Algorithms Settings Other commands plot: viewing data info: show information commands, dump, sleep, reset, quit Using and extending Use cases Extensions How to add your own built-in function A. 6 Functions and variables in data transformation. You could get good theoretical approximations of the error function using Most languages seem to have a way to link in C functions, and if that is the case, then there is an open source implementation somewhere out there. Chebyshev polynomials come to mind.Īs for the problem that the language your writing in has no such library already: for me that is probably not as big of a deal as you think. Once you have a compact domain, you can know exactly how many Taylor terms you need, or you can use other types of spline interpolation. If you size it properly, then the function will appear constant with respect to your machine precision outside of this interval. For larger values you could use the asymptotic series.Īnother idea would be to restrict the domain to a closed interval. Numerical approximation might lead to a larger error term than the analytic one though, and it will only be valid in a neighborhood of 0. Other than that, I would try the Taylor series. And it looks like their error is within a few multiples of the machine epsilon.

It's all fairly well documented should you care to duplicate their method.

They use their implementation of the incomplete gamma function, which in turn uses a mixed approach depending on the argument. Here's a link to the boost c++ math library documentation.