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5. Version history: We recommend the latest version SZ 1.0.5.13

  • SZ 0.2-0.4 Compression ratio is the same as SZ 0.5. The key difference is different implementation ways, such that SZ 0.5 is much faster than SZ 0.2-0.4.
  • SZ 0.5.1 Support version checking

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  • SZ 0.5.10 optimizes the offset by using the optimized formula of computing the median_value based on optimized right-shifting method. Anyway, this version improves compression ratio a lot for hard-to-compress datasets. (Hard-to-compress datasets refer to the cases whose compression ratios are usually very limited)
  • SZ 0.5.11 improved SZ 0.5.10 on the level of guaranteeing user-specified error bounds. In a very few cases, SZ 0.5.10 cannot guarantee the error-bounds to a certain user-specified level. For example, when absolute error bound = 1E-6, the maximum decompression error may be 0.01(>>1E-6) because of the huge value range even in the optimized segments such that the normalized data cannot reach the required precision even storing all of the 64 or 32 mantissa bits. SZ 0.5.11 fixed the problem well, with compression ratio degraded by less than 1% in that case. 
  • SZ 0.5.12 allows users to set "offset" parameter in the configuration file sz.config. The value of offset is an integer in [1,7]. Generally, we recommend offset=2 or 3, while we also find that some other settings (such as offset=7) may lead to better compression ratios in some cases. How to automize/optimize the selection of offset value would be the future work. In addition, the compression speed is improved, by replacing java List by array implementation in the code.
  • SZ 0.5.13 improves compression performance, by replacing the implementation with classes by that of primitive data types.
  • SZ 0.5.14 fixed a design bug, which improves the compression ratio further.
  • SZ 1.0 C version

6. Download

-->>> Code download <<<-- (soon, pending DoE approval of distribution licencelicense)

(The code is ready to use, but it cannot be released now because the BSD license is under approval process. Before the official release, the code is available upon request. Contact: disheng222@gmail.com or sdi1@anl.gov)

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