Retrieval
If you wish to utilize the knowledge implicitly contained in your Knowledge Base (i.e. your collection of known spectra) for analyzing a new spectrum
of some unknown sample, the primary method is to have the spectrum
classified by PATTERN EXPERT airspect. However, there is yet another reasonable task:
Search the Knowledge Base for one or more reference spectra, which are most similar to the given unknown spectrum ("retrieval"). Here, similarity is defined
by some appropriate measure of the distance between two spectra. That is, the retrieval task consists of finding those reference spectra in the
Knowledge Base, which are "nearest" to the unknown one. Of course, the results depend significantly on the selected distance measure.
For the retrieval tools included in the software PATTERN EXPERT airspect you may select from five different distance measures. These measures prove to yield excellent results,
which compare to those of human experts.
For each given unknown spectrum, you obtain a hit list of reference spectra ordered by similarity.
In addition, the software provides several different diagrams for a visual comparison of the unknown spectrum and the reference spectra.
Spectroscopy Techniques 
