Multipeak fitting ExpModGauss function

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Wed, 05/23/2012 - 10:24 am

Hi,

Can anybody tell me where to find the functions for ExpModGauss and ExpConvExp used in Multipeak Fitting 2? I am a Chemist by trade and so not very experienced when it comes to programing/code. All I am looking to do is to use the peak fitting tool to fit a curve to my spectra, giving me FWHM and area information (ease enough), and then use the equation of the curve to calculate at what time (x-axis) my peak reaches a percentage of my peak maximum.

Any help will be greatly appreciated.
Dave
The function definitions are in the PeakFunctions2.ipf procedure window when you have Multipeak Fit 2 loaded. To view it, select Windows->Procedure Windows->PeakFunctions2.ipf.

I think there is no analytic way to find the location of a given amplitude value. The Multipeak Fit 2 package finds the FWHM of ExpModGauss using a numerical root solver. To see how that is done, see the function GaussConvExpFWHM(). It also uses numerical techniques to find the actual peak location. That is done by the function GaussConvExpFindAmpLoc(), which finds the location of the peak and returns both the location and the true peak amplitude via the amp and loc parameters.

The peak location of the ExpConvExp peak shape is computable. See the function expexp_Location(). The location of a given amplitude is not; similarly to the ExpModGauss peak shape, it is done numerically. See the ExpExpFWHM() function.

John Weeks
WaveMetrics, Inc.
support@wavemetrics.com

May 23, 2012 at 11:34 am - Permalink