Short description of IEP (File READ.ME)                             20.06.95

Programs by Markus Neher
            Institute of Applied Mathematics
            Karlsruhe University
            D-76128 Karlsruhe, Germany
            e-mail: markus.neher@math.uni-karlsruhe.de

IEP is a programming system for the reconstruction of Sturm-Liouville
potentials. IEP consists of the main programs

 - IEPS_AGP  for the reconstruction of spline potentials
 - IEPT_AGP  for the reconstruction of potentials
             with a finite trigonometric expansion,

the modules

 - SEIG_APP  PASCAL-XSC modules
 - SEIG        for matrix-eigenvalue problems
 - SERVICE   Basic routines
 - SPLINES   Spline routines
 - IEP_TAYK  Taylor arithmetic
 - IEP_RAWA  Approximate solution of ivps
 - IEP_IAWA  Guaranteed solution of ivps
 - DEP       Computation of eigenvalues and eigenfunction
 - DEPT        of the Sturm-Liouville equation

and the files

 - RITZG07.30
 - RITZU07.30

for the Ritz matrices for spline potentials with 7 breakpoints in [0,\pi]
(for less or more breakpoints, the corresponding Ritz matrices have to be
supplied in other files).

To use IEP, first compile the modules in the given order, then compile the
main programms. The eigenvalues and coefficients of a starting potential
have to be entered by files.

Examples for the running of the programs:

   IEPS_AGP XSQR0100.EWB SPOTQ.VAL CON RESULTS.TXT
        --> reads eigenvalues from the file XSQR0100.EWB
        --> reads function values in the braekpoints of a spline
                  from the file SPOTQ.VAL
        --> writes control messages to the console
        --> writes results to the file RESULTS.TXT

   IEPT_AGP COS10010.EWB TPOTQ.COE CON RESULTS.TXT
        --> reads eigenvalues from the file COS10010.EWB
        --> reads coefficients of a trigonometric starting potential
                  from the file TPOTQ.COE
        --> writes control messages to the console
        --> writes results to the file RESULTS.TXT

The sample input files XSQR0100.EWB, COS10010.EWB, SPOTQ.VAL and TPOTQ.COE are
provided with the program files mentioned above and this short description.