# 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)


## Arguments

   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.