Symbolic perturbation by innnitely small values removes degeneracies in geometric algorithms and enables programmers to handle only generic cases: there are a few such cases, whereas there are an overwhelming number of degenerate cases. Current perturbation schemes have limitations, presented below. To overcome them, this paper proposes to use an-arithmetic, i.e. to represent in an explicit way...

Properly phased combinations of images reconstructed from holograms recorded at several wavenumbers suppress inter-object multiple scattering, self-interference, and the troublesome holographic twin image. When applied to point-source electron holographies, this solves the long-standing problem of electron multiple scattering confusing the determination of surface structure; when applied to in-...

In this contribution, a method is described for the attenuation of preecho in audio recordings. Preechos are attenuated replicas of the future signal that can usually be heard in tape or phonograph recordings in silences or near-silences preceding sudden, high amplitude sounds. The method described here is based on a very simple attenuation+delay preecho model. The delay is estimated by use of ...