Smooths each spectral row by penalized least squares with the standard second-difference penalty. Lambda controls the balance between fidelity and smoothness, and the preview updates continuously while the slider is dragged. The GUI supports sample inspection, guarded opt-in display of all spectra, cached Cholesky solves, batch application, and export of the full smoothed matrix and metadata. It requires MATLAB R2022a or later with no additional toolbox.
Eilers, P. H. C. (2003). A perfect smoother. Analytical Chemistry, 75(14), 3631-3636.
