491 research outputs found
New Exact and Numerical Solutions of the (Convection-)Diffusion Kernels on SE(3)
We consider hypo-elliptic diffusion and convection-diffusion on , the quotient of the Lie group of rigid body motions SE(3) in
which group elements are equivalent if they are equal up to a rotation around
the reference axis. We show that we can derive expressions for the convolution
kernels in terms of eigenfunctions of the PDE, by extending the approach for
the SE(2) case. This goes via application of the Fourier transform of the PDE
in the spatial variables, yielding a second order differential operator. We
show that the eigenfunctions of this operator can be expressed as (generalized)
spheroidal wave functions. The same exact formulas are derived via the Fourier
transform on SE(3). We solve both the evolution itself, as well as the
time-integrated process that corresponds to the resolvent operator.
Furthermore, we have extended a standard numerical procedure from SE(2) to
SE(3) for the computation of the solution kernels that is directly related to
the exact solutions. Finally, we provide a novel analytic approximation of the
kernels that we briefly compare to the exact kernels.Comment: Revised and restructure
Symmetrized Perturbation Determinants and Applications to Boundary Data Maps and Krein-Type Resolvent Formulas
The aim of this paper is twofold: On one hand we discuss an abstract approach
to symmetrized Fredholm perturbation determinants and an associated trace
formula for a pair of operators of positive-type, extending a classical trace
formula. On the other hand, we continue a recent systematic study of boundary
data maps, that is, 2 \times 2 matrix-valued Dirichlet-to-Neumann and more
generally, Robin-to-Robin maps, associated with one-dimensional Schr\"odinger
operators on a compact interval [0,R] with separated boundary conditions at 0
and R. One of the principal new results in this paper reduces an appropriately
symmetrized (Fredholm) perturbation determinant to the 2\times 2 determinant of
the underlying boundary data map. In addition, as a concrete application of the
abstract approach in the first part of this paper, we establish the trace
formula for resolvent differences of self-adjoint Schr\"odinger operators
corresponding to different (separated) boundary conditions in terms of boundary
data maps.Comment: 38 page
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