FindGraph: Fit peaks by selecting method or providing parameters

Fit Peaks

Follow these steps::

1. Select data series on left panel [Points].
2. Select menu item <Fit><Find Peaks>.
3. The 'Peak Fitting' Wizard appears. Wizard guides you through each step of the peak fitting process.
4. On first step specify a sub-range of the data.
5. On step 2 specify and subtract a baseline. FindGraph supports a constant baseline (offset), a line in fixed points, a cubic polynomial, or an exponential to fit peaks with a baseline function. The initial baseline points can be set in several ways. An automated FFT smoothing is applied to find all local minimum to define baseline. You can interactively draw or edit this points with the mouse. You can use other FindGraph baseline modeling tools to specify and subtract out the baseline before the fit.
6. On step 3 specify peak locations automatically or manually, or both. The initial values for the fit, i.e., the number, X placement, height, and semi-width of the peaks can be set. Up to 15 peaks are supported. Automatically locate peaks by specifying a threshold width of peaks. FindGraph initially places peaks by finding all local maximum in a smoothed data stream. Manually locate peaks by point-and-click with the mouse.
7. You can delete the current peak, insert a new peak or edit an old peak. It is possible to display the smoothed second derivative of your data. It may be helpful in finding hidden peaks. The Savitzky-Golay smoothing method is used with the polynomial degree 2, the span is equal to 5% of the number of data points. If you know that two or more peaks must be separated by a certain interval, fit each peak near its initial X placement in semi-width interval only.
8. On step 4 choose peak function, and perform your fit.. FindGraph can fit multiple overlapping peaks using one of 20 basic peak fit types: Gaussian, Lorentzian, Voigt, ExpGaussian, Asymmetric Gaussian, Inverse Polynomial, Edgeworth-Cramer, and more. FindGraph adjusts the X placement, width, height, and symmetry to fit peaks.
9. New graph appears. Click More and on page Plot see how curve fit conforms your data. The residuals plot is very handy in deciding whether the fit is good or whether there may be additional peaks. The baseline can be shown as well.
10. On step 5 select line color and click Add Line.
11. Close the dialog and select menu item <View><Fitting log>.