Università della Svizzera italiana

Space–time shape uncertainties in the forward and inverse problem of electrocardiography

Gander, Lia ; Krause, Rolf ; Multerer, Michael ; Pezzuto, Simone

In: International journal for numerical methods in biomedical engineering, 2021, vol. 37, no. 10, p. 23

In electrocardiography, the “classic” inverse problem is the reconstruction of electric potentials at a surface enclosing the heart from remote recordings at the body surface and an accurate description of the anatomy. The latter being affected by noise and obtained with limited resolution due to clinical constraints, a possibly large uncertainty may be perpetuated in the inverse ...

Università della Svizzera italiana

A fast direct solver for nonlocal operators in wavelet coordinates

Harbrecht, Helmut ; Multerer, Michael

In: Journal of computational physics, 2021, vol. 428, p. 15 p

In this article, we consider fast direct solvers for nonlocal operators. The pivotal idea is to combine a wavelet representation of the system matrix, yielding a quasi- sparse matrix, with the nested dissection ordering scheme. The latter drastically reduces the fill-in during the factorization of the system matrix by means of a Cholesky decomposition or an LU decomposition, respectively. This...