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52 lines
2.4 KiB
Plaintext
52 lines
2.4 KiB
Plaintext
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Dear UDUNITS user,
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Version 2 of the UDUNITS package is now available from the UDUNITS
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homepage at <http://www.unidata.ucar.edu/software/udunits/>.
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The UDUNITS-2 package differs from the previous UDUNITS package in the
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following ways:
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Support for non-ASCII characters. The original UDUNITS package only
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supports the ASCII character set. The UDUNITS-2 package supports
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the following character sets: ASCII, ISO 8859-1 (Latin 1), and the
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UTF-8 encoding of ISO 10646 (Unicode). This means that unit string
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specifications like "µ°F·Ω⁻¹" are now supported (your viewer
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must support UTF-8 to display this string correctly).
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Support for logarithmic units. The unit string specification
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"0.1 lg(re 1 mW)" specifies a deciBel unit with a one milliwatt
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reference level. Meteorologists should note that the unit "dBZ"
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(i.e., "0.1 lg(re um^3)") is now supported.
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Persistent value converters. It is now possible to obtain a converter
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data-object, which can be used to convert numeric values in one
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unit to numeric values in another, compatible unit. The values can
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be float, double, or one-dimensional arrays of floats or doubles.
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Improved API. Due to the above changes, it was not possible to keep
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the application programming interface of the original UDUNITS
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package. Beginning with version 2.1.0, however, the package
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contains a thin UDUNITS API to the UDUNITS-2 library, so code
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written to the original API can simply be recompiled and relinked
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against the new package. Because the original UDUNITS API uses the
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"utUnit" data-structure and the UDUNITS-2 API uses pointers to
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"ut_unit" data-structures, a small memory-leak is possible in code
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that creates many units. This leak can be avoided by calling the
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new method utFree(utUnit*) when the unit is no longer needed.
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XML unit database. The unit database is encoded using human-readable
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XML rather than a custom format. The XML parser included in the
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package supports an <import> element to allow easy and convenient
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customization.
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One thing that has not changed is that all unit string specifications
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understood by the original UDUNITS package are also understood by the
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new UDUNITS-2 package.
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Please visit the webpage or email <support-udunits@unidata.ucar.edu> if
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you have questions or comments.
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Regards,
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Steve Emmerson
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UDUNITS-2 Developer
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