Eigenvalues Sought.

We give three typical cases:

``IE''

stands for one or a few isolated eigenvalues at the end of the spectrum.

``CE''

stands for one or several eigenvalues at the end of the spectrum, possibly clustered, a typical example being computing the lowest eigenmodes of a vibrating mechanical system, modeled by finite element methods.

``M''

means some eigenvalues in the middle of the spectrum, most often in a specified interval, such as seeking all eigenmodes of a mechanical or electrical system excited by an external load of a prescribed frequency.