The following technical report is available from
http://aib.informatik.rwth-aachen.de:
Algorithmic Differentiation of Numerical Methods: Tangent-Linear and
Adjoint Direct Solvers for Systems of Linear Equations
Uwe Naumann and Johannes Lotz
AIB 2012-10
We consider the Algorithmic Differentiation (also know as Automatic
Differentiation; AD) of numerical simulation programs that contain calls
to direct solvers for systems of n linear equations. AD of the linear
solvers yields a local overhead of O(n^3) for the computation of
directional derivatives or adjoints of the solution vector with respect
to the system matrix and right-hand side. The local memory requirement
is of the same order in adjoint mode AD. Mathematical insight yields a
reduction of the local computational complexity to O(n^2). The memory
overhead can be reduced to at least O(n^2) in adjoint mode. We derive
efficient tangent-linear and adjoint direct linear solvers and
illustrate their use within tangent-linear and adjoint versions of the
enclosing numerical simulation.