# reduce.m

From Spinach Documentation Wiki

Symmetry and trajectory-level state space reduction. Tries all applicable reduction methods (unless disabled during the call to create.m) and returns a cell array of projectors into a set of independently evolving reduced subspaces.

## Contents

## Syntax

projectors=reduce(spin_system,L,rho)

## Arguments

L - Liouvillian matrix rho - initial state (source state screening) or destination state (destination state screening)

## Outputs

projectors - a cell array of projectors into independently evolving reduced subspaces. The projectors are to be used as follows: L_reduced=P'*L*P; (for matrices) rho_reduced=P'*rho; (for state vectors)

## Notes

Further information on what this function does is available in our papers on this subject

http://dx.doi.org/10.1016/j.jmr.2008.08.008 http://dx.doi.org/10.1063/1.3398146 http://dx.doi.org/10.1016/j.jmr.2011.03.010

Briefly, the function tries symmetry factorisation, followed by zero track elimination, followed by disconnected subspace identifcation by path tracing.

## See also

zte.m, path_trace.m, symmetry.m, perm_group.m

*Version 2.2, authors: Ilya Kuprov, Luke Edwards, Matthew Krzystyniak*