# Zte.m

Zero track elimination function. Inspects the first few steps in the system trajectory and drops the states that did not get populated to a user-specified tolerance. The default tolerance may be altered by set- ting sys.tols.zte_tol variable before calling create(). Syntax:

               projector=zte(spin_system,L,rho,nstates)


Parameters:

     L       - the Liouvillian to be used for time propagation

     rho     - the initial state to be used for time propagation

     nstates - if this parameter is specified, only nstates most
populated states are kept, irrespective of the to-
lerance parameter


Output:

     projector - projector matrix into the reduced space, to be used
as follows: L_reduced=P'*L*P, rho_reduced=P'*rho;


Further information is available in IK's JMR paper on the subject:

             http://dx.doi.org/10.1016/j.jmr.2008.08.008


## Notes

It is a good idea to disable ZTE in systems with nearly equivalent spins.