CURRENT ARTICLES: VOLUME 15

This article presents a mathematical model for generating annoying scratching sounds. Such sounds are generated by frictional motion and have been attributed to the chaotic nature of the frequency spectrum thereby produced. The proposed model is based on the logistic map and is modified to have the stick-slip property of a frictional vibration. The resulting sound is similar to that generated by scratching a chalkboard or glass plate with the fingernails. Read More »

This article is an excerpt from the recently released book, Programming with Mathematica: An Introduction by Paul Wellin © 2013 [1]. The book, which follows on the well-known An Introduction to Mathematica Programming, provides an example-driven primer on the foundations of the Mathematica programming language.

Strings are used across many disciplines to represent filenames, data, and other objects: linguists working with text data study representation, classification, and patterns involved in audio and text usage; biologists dealing with genomic data as strings are interested in sequence structure and assembly and perform extensive statistical analysis of their data; programmers operate on string data for such tasks as text search, file manipulation, and text processing. Strings are so ubiquitous that almost every modern programming language has a string datatype and dozens of functions for operating on and with strings. Read More »

The NXT is a general-purpose processor that can be used to control motors and sensors; it is ideal for building autonomous robots. It can also communicate with more elaborate software located on a computer, using a Bluetooth communication port. In this article, we show how to communicate with the NXT by sending the correct bytes. We also introduce a package that manages all the exchanges through functions. These functions can be used in conjunction with dynamic cells to display the robot’s status and control the robot’s motor. Read More »

The motivation for this article lies in 3D computer graphics animation systems that were developed twenty to thirty years ago. The author particularly sees the connection between Mathematica and the animation system that ran in Genera Lisp on the Symbolics platform. This article presents a method for programmatically operating on an animation scene graph in Mathematica represented in the X3D extension of the Extensible Markup Language (XML). Below is presented historical and conceptual background on the animation scene graph and a contemporary example. Further motivation came from comparing the user interface design of a current, advanced animation system to an animation scene graph implemented in X3D and uploaded to Wolfram|Alpha Pro. Finally, this article presents an instance where an X3D scene graph was used in the “Fingerspelling Sign Language” Demonstration [1]. Read More »

II. Kinetic-Energy Integrals

This article carries out the evaluation of kinetic energy integrals using Gaussian-type functions with arbitrary Cartesian angular values. As an example, we calculate the kinetic matrix for the water molecule in the STO-3G basis set. Read More »