5.1 Numerical routines and libraries: overview
For the Laplace transform inversion three numerical methods can be used: Contin, Flog, and Ftikreg. All of them use the so-called Tikhonov regularisation method for the inverse Laplace transform approximation (see the Introduction for information about the advantages and disadvantages of this approach for the DLTS measurements). The numerical routines are used as Dynamically Linked Libraries (DLL), which means that they can exchange data with the main application through the computer memory with no input and output files. This means that they can be run in either a synchronous or asynchronous mode. In asynchronous computations the main application passes the control of the computation process to another application (Calculation Dispatcher program RExeTris) which manages the computation queue, monitors the progress for each particular data file, and finally, if the computations are successful, creates the spectrum file.
As a part of a preliminary data analysis, there is the fourth numerical method (Fast_DC). It is not a true Laplace inversion method because it uses the Tittelbach-Helmrich approach. This only calculates the discrete exponential components in the transient. This method can be only used synchronously but the spectrum can also be stored and recorded in the Data base.
5.1.1 Tikhonov regularisation method