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**A comment on the presentation and testing of CALGO codes and a remark on algorithm 639**: To integrate some infinite oscillating tails

Tim Hopkins

Pages: 285-300

DOI: 10.1145/569147.569148

We report on a number of coding problems that occur frequently in published CALGO software and are still appearing in new algorithm submissions. Using Algorithm 639 as an extended example, we describe how these types of faults may be almost entirely...

**Recent advances in direct methods for solving unsymmetric sparse systems of linear equations**

Anshul Gupta

Pages: 301-324

DOI: 10.1145/569147.569149

During the past few years, algorithmic improvements alone have reduced the time required for the direct solution of unsymmetric sparse systems of linear equations by almost an order of magnitude. This paper compares the performance of some well-known...

**Algorithm 819: AIZ, BIZ**: two Fortran 77 routines for the computation of complex Airy functions

Amparo Gil, Javier Segura, Nico M. Temme

Pages: 325-336

DOI: 10.1145/569147.569150

Two Fortran 77 routines for the evaluation of Airy functions of complex arguments *Ai*(*z*), *Bi*(*z*) and their first derivatives are presented. The routines are based on the use of Gaussian quadrature, Maclaurin series and...

**Algorithm 820**: A flexible implementation of matching pursuit for Gabor functions on the interval

Sebastian E. Ferrando, Lawrence A. Kolasa, Natasha Kovačević

Pages: 337-353

DOI: 10.1145/569147.569151

In digital signal processing it is often advantageous to analyze a given signal using an adaptive method. The signal is approximated or represented as a superposition of "basic" waveforms chosen from a *dictionary* of such waveforms so as to...

**Algorithm 821**: A Fortran interface to POSIX threads

Richard J. Hanson, Clay P. Breshears, Henry A. Gabb

Pages: 354-371

DOI: 10.1145/569147.569152

Pthreads is the library of POSIX standard functions for concurrent, multithreaded programming. The POSIX standard only defines an application programming interface (API) to the C programming language, not to Fortran. Many scientific and engineering...

**Remark on algorithm 705**: A Fortran-77 software package for solving the Sylvester matrix equation *AXB*^{T} + *CXD*^{T} = *E*

Tim Hopkins

Pages: 372-375

DOI: 10.1145/569147.569153

We present a number of corrections to Algorithm 705 [Gardiner et al. 1992].