A shape factor of zero is pure Gaussian with the Lorentzian contribution increasing as shape increases. It includes a shape parameter that adjusts the relative contribution of the two. All the peaks except LogNormal have their location parameter set at zero.Ī Voigt is the convolution between a Gaussian and a Lorentzian.
Graphpad prism 5 smooth curve full#
The various peak types shown here (except LogNormal) have been adjusted to have the same Full Width at Half Max. The following graph illustrates the different types: You can use any mix of these peak types while fitting a single data set. The ExpModGauss function is also known as Exponentially Modified Gaussian. This package can fit multiple overlapping peaks using any of six basic peak fit types: Gaussian, Lorentzian, Voigt, ExpModGauss, ExpConvExp and LogNormal.
Note: fitting to overlapping peaks has often been called "deconvolution." This is not strictly correct as the peaks are merely added together and not convolved in the mathematical sense. In the result shown above the residuals are just noise indicating a good fit. The residuals plot (at the top in the graph above) is very handy in deciding whether the fit is good or whether there may be additional peaks lurking in the data. Individual peaks, the overall fit trace and baseline are included on the graph. You can have as many different graphs and data sets under analysis simultaneously as you want since each graph has its own control panel. This control panel controls most aspects of choosing peak types and generating initial guesses. When you click Continue, the result is a graph with an associated control panel "stuck" to the graph. In the resulting control panel, choose your x and y data. To start, you select Start New Multi-peak Fit from the Analysis menu.
Fit any number of peaks in one data set.This package, like many others included with Igor, can be accessed simply by choosing a menu item. If you have spectroscopic, chromatographic or other forms of data containing multiple, often overlapping peaks, you will appreciate Igor's multi-peak fitting package. Wide-Angle Neutron Spin Echo Spectroscopy.
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