Release of NeXus v1.3.0 with data compression

[Ray Osborn]

Following popular demand, Mark Koennecke has updated the NeXus API to
include data compression.  Users can choose to compress using either LZW
(gzip), Skipping Huffman, or Run-Length Encoding algorithms.

In the core API, compression is invoked by a call to NXcompress between
calls to NXopendata and NXputdata or NXputslab.  Data is automatically
compressed in NXUwritedata (currently only a part of the F90 Utility API) if
there has been a call to NXUsetcompress, which defines the compression
algorithm and the minimum size of data set to be compressed (it makes no
sense to compress very small arrays).  See the web pages at
<http://www.neutron.anl.gov/NeXus/> for more details.

One of the beauties of using HDF to do the data compression is that it
automatically decompresses the data when you read them back.  There is no
need therefore to rewrite any data input routines.
    
The scale of compression you get will depend on the type of data you have,
but if the NeXus file is dominated by a few large data sets, you can get an
idea of what you should achieve by gzipping the whole file.

The current version of the API is v1.3.0.  Please send messages to this list
if you have any useful experience (positive or negative) to report, and
definitely report any bugs.

Ray Osborn

P.S. I have been unable to update all of the NeXus web pages on our NT
server here at Argonne for a currently unknown reason.  We are trying to
sort out the problem now, but in the meantime, use the European mirror until
the home page shows today's date at the bottom.

-- 
Dr Ray Osborn                Tel: +1 (630) 252-9011
Materials Science Division   Fax: +1 (630) 252-7777
Argonne National Laboratory  E-mail: ROsborn at anl.gov
Argonne, IL 60439-4845