A Brief Introduction to XTide

This article introduces a program that produces output in text mode, graphics and Java. Besides all that, XTide is both useful and fun.
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An illustrated version of the XTide README can be accessed at universe.digex.net/~dave/xtide/. It contains examples of almost every kind of output that XTide can generate and includes full instructions and a FAQ.

You can learn a lot about tides and tide prediction by reading the National Ocean Service's Tide and Current Glossary. An old version is preserved at universe.digex.net/~dave/xtide/tidegloss.html for the purpose of providing definitions for the technical terms used in the XTide README. The latest version, currently accessible at www-ceob.nos.noaa.gov/tidegloss.html, has been separated into many smaller web pages for easier browsing.

The canonical reference for tide prediction is the Manual of Harmonic Analysis and Prediction of Tides, Special Publication No. 98, Revised (1940) Edition, United States Government Printing Office, 1941. However, much of the traditional lore on tide prediction is not digestible unless you like swimming through pages of equations. Probably the easiest introduction to the subject for programmers is to read the source for the Java applets provided in the XTide distribution. These were written to be as small and simple as possible, and you can easily see where the tides are generated.

Although tide prediction is almost a definition of the term niche market, XTide has attracted an amazing number of users, and I hope that it will continue to serve their needs for years to come.

David Flater (dave@universe.digex.net) is a Computer Scientist (actual job title) living in the vicinity of Washington, D.C. He escaped grad school two years ago with a Ph.D. in Computer Science and is still trying to regain his sense of humor. All things considered, he'd rather be John Carmack.


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