expmint.m

Computes matrix exponential integrals of the following general type:

            Integrate[expm(-i*A*t)*B*expm(i*C*t),{t,0,T}]

Matrix A must be Hermitian. For further info see the paper by Charles van Loan (http://dx.doi.org/10.1109/TAC.1978.1101743).

Syntax

    R=expmint(spin_system,A,B,C,T)

Parameters

   A,B,C   - the three matrices involved in the integral

       T   - integration time

Outputs

       R   - the resulting integral

Notes

The auxiliary matrix method is massively faster than either commutator series or diagonalisation.

This is the most memory-intensive stage in many calculations; memory recycling is aggressive.

See also

intrep.m, propagator.m, average.m, rotframe.m, dirdiff.m

Version 2.2, authors: Luke Edwards, David Goodwin, Ilya Kuprov