Day: May 1, 2012

Program of the month: sfderiv

May 1, 2012 Programs 14 comments

sfderiv applies the first derivative filter.

The algorithm implemented in this program is described in the paper

Pei, S.-C., and P.-H. Wang, 2001, Closed-form design of maximally flat FIR Hilbert transformers, differentiators, and fractional delayers by power series expansion: IEEE Trans. on Circuits and Systems, v. 48, No. 4, 389-398.

It is based on the Taylor expansion of the inverse sine function
$$\arcsin{x} = \displaystyle \sum_{n=0}^{\infty} \frac{(2n)!}{4^n\,(n!)^2\,(2n+1)}\,x^{2n+1}$$
which turns into an expansion of the ideal derivative filter into a chain of digital filters. The order= parameter controls the order of the expansion and the accuracy-efficiency trade-off. The following example from rsf/rsf/sfderiv shows the frequency responses and the impulse responses for differentiators of different orders

An alternative is sfigrad, which implements a simple first-order derivative. igrad is more efficient and adequate when computing derivatives of smooth functions.

Previous programs of the month

Performance evaluation of SU and Madagascar

May 1, 2012 Links No comments

The paper Performance Evaluation of Open Source Seismic Data Processing Packages by Izzatdin A. Aziz, Andrzej M. Goscinski, and Michael M. Hobbs from Deakin University was presented at the 11th International Conference on Algorithms and Architectures for Parallel Processing (ICA3PP 2011).

“The goal in this paper was to demonstrate the capability of open source packages, SU and Madagascar, to execute a sequence of seismic functions representing the actual industrial work process. We succeeded in this by conducting two sets of tasks. First, the investigation of the problem, whether or not open source seismic data processing packages can be executed using the same set of seismic data through data format conversions. Second, whether or not they can achieve reasonable performance and speedup when execute parallel seismic functions on a HPC cluster.”