1992 18.09 1994

Vol.18 n°9 (#204) september 1993

(ddj_1993_09.jpg)

p.6 EDITORIAL

[author : Jonathan Erickson] #Edito

TABLE OF CONTENTS

FEATURES

p.18 RECURSIVE WORLDS

[author : Clifford A. Pickover]

Recursion is fundamental to computer science, mathematics, biology, art, and even linguistics. Cliff examines recursive lattices, classes of self-similar objects that can easily be constructed using checkerboards of different sizes.

p.28 ARBITRARY PRECISION FLOATING-POINT ARITHMETIC

[author : Frederick C. Motteler]

Here's a general-purpose C library for extended precision and IEEE-754 compatibility. The K&R/ANSI C/C++ compatible package supports single, double, double-extended, and longer, IEEE-754-like formats and is portable across operating systems including UNIX and MS-DOS.

p.36 ALGEBRA AND THE LAMBDA CALCULUS

[author : Aubrey Jaffer]

Aubrey describes how he implemented lambda calculus in "Jacal," a symbolic mathematics system for the simplification and manipulation of equations.

p.42 EXAMINING THE WINDOWS AARD DETECTION CODE

[author : Andrew Schulman]

Andrew takes a close look at the Windows "AARD" code which, under certain conditions, can generate a mysterious error message.

EMBEDDED SYSTEMS

p.50 THE Z80180 AND BIG-NUMBER ARITHMETIC

[author : Burton S. Kaliski, Jr.]

There's nothing difficult about performing big-number arithmetic on powerful 32-bit processors like the 486 or Pentium. But where do you start if you want to implement 512-bit operations on 8-bit controllers? That's the problem Burt recently faced—and here's his solution.

NETWORKED SYSTEMS

p.60 ACCESSING NETWARE SQL FILES WITHOUT NETWARE SQL

[author : Douglas Reilly]

Doug shares techniques that let you use Btrieve, NetWare's SQL file-manager engine, to duplicate the functionality of NetWare SQL. This gives access to NetWare SQL files without requiring your users to have NetWare SQL.

EXAMINING ROOM

p.68 PORTING FROM WORKSTATIONS TO PCs

[author : Barr E. Bauer]

Porting compute- and data-intensive Fortran applications from high-performance workstations to low-cost PCs has been a promise waiting for fulfillment. Barr describes his experiences in porting a simulated-annealing program, originally written for the VAX, to a 386SX platform.

PROGRAMMER'S WORKBENCH

p.76 MODELING SYSTEMS WITH POLYNOMIAL NETWORKS

[author : Peter D. Varhol]

Polynomial networks, which are based on the premise that different combinations of polynomials can minimize the error between derived and expected outputs, enable you to quickly build systems for predicting behavior.

COLUMNS

p.99 PROGRAMMING PARADIGMS

[author : Michael Swaine]

According to Michael, AppleScript is Apple's idea of what a scripting system can and ought to be, at least on a 1993-vintage graphical user interface and operating system.

p.105 C PROGRAMMING

[author : Al Stevens]

Al examines the next hot C++ language feature—exception handling. As he explains, exception handling allows one part of a program to detect and report exceptional conditions and another part to handle them.

p.115 ALGORITHM ALLEY

[author : Tom Swan]

Last month, Tom introduced algorithms and test programs for compressing and decompressing Windows bitmap files. This month, he presents the remaining test programs and a C++ utility that compresses real 256-color bitmap files.

p.119 UNDOCUMENTED CORNER

[author : Andrew Schulman]

In this first installment of a two-part article, Pete Davis documents the undocumented Windows .HLP file format. This month, Pete explains the basics of the "WHIFS" B-tree system, and explains a few of the internal files.

p.127 PROGRAMMER'S BOOKSHELF

[author : Lynne Greer Jolitz]

While you can't keep network systems and data under lock and key, there are security techniques you can still employ. Lynne examines the approaches presented in UNIX System Security and UNIX Installation, Security, and Integrity.

FORUM

p.10 LETTERS

[author : you]

p.144 SWAINE'S FLAMES

[author : Michael Swaine]

PROGRAMMER'S SERVICES

p.138 OF INTEREST