24 lines
1.4 KiB
Text
24 lines
1.4 KiB
Text
XTide is a package that provides tide and current predictions in a
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wide variety of formats. Graphs, text listings, and calendars can be
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generated, or a tide clock can be provided on your desktop. XTide can
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work with X-windows, plain text terminals, or the web. This is
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accomplished with three separate programs: the interactive interface
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(xtide), the non-interactive or command line interface (tide), and the
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web interface (xttpd).
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The algorithm that XTide uses to predict tides is the one used by the
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National Ocean Service in the U.S. It is significantly more accurate
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than the simple tide clocks that can be bought in novelty stores.
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However, it takes more to predict tides accurately than just a spiffy
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algorithm -- you also need some special data for each and every
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location for which you want to predict tides. XTide reads this data
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from harmonics files. Ultimately, XTide's predictions can only be as
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good as the available harmonics data. Due to issues of data
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availability and of compatibility with non-U.S. tide systems, the
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predictions for U.S. locations tend to be a lot better on average
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than those for locations outside of the U.S.
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* Deviations of 1 minute from official predictions are typical for U.S.
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locations having the latest data.
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* Deviations of 20 minutes are typical for non-U.S. locations or U.S.
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locations that are using obsolete data.
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* Much longer deviations indicate a problem.
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