Hi Jarom, In case it might help, there are C and Fortran code examples in the User's Guide that do almost exactly what Francesc mentioned. See Section 6.5.2.2.1 in the "HDF5 Datatypes" chapter of the HDF5 User's Guide. The link to section 6.5.2 is:
https://support.hdfgroup.org/HDF5/doc/UG/HDF5_Users_Guide-Responsive%20HTML5/index.html#t=HDF5_Users_Guide%2FDatatypes%2FHDF5_Datatypes.htm%23TOC_6_5_2_Definition_ofbc-14&rhtocid=6.3.0_2 Scroll down to 6.5.2.2.1, "Compound Datatypes". Scroll down a little further and you will see "Code Example 6-9" for C and "Code Example 6-10" for Fortran. -Barbara From: Hdf-forum [mailto:[email protected]] On Behalf Of Francesc Altet Sent: Wednesday, February 22, 2017 2:02 AM To: HDF Users Discussion List Subject: Re: [Hdf-forum] Complex numbers (1.10.x update?) Hi Jarom, For what is worth, in PyTables and h5py (and possibly in others libraries too) we used the convention of declaring the complex type by using a compound type as follows: """ The H5T_COMPOUND type class contains two members. Both members must have the H5T_FLOAT atomic datatype class. The name of the first member should be "r" and represents the real part. The name of the second member should be "i" and represents the imaginary part. The precision property of both of the H5T_FLOAT members must be either 32 significant bits (e.g. H5T_NATIVE_FLOAT) or 64 significant bits (e.g. H5T_NATIVE_DOUBLE). They represent Complex32 and Complex64 types respectively. """ Perhaps you may want to use this convention until a more formal one is implemented. Francesc Alted ________________________________ From: Hdf-forum <[email protected]<mailto:[email protected]>> on behalf of Nelson, Jarom <[email protected]<mailto:[email protected]>> Sent: Wednesday, February 22, 2017 2:36:23 AM To: HDF Users Discussion List Subject: Re: [Hdf-forum] Complex numbers (1.10.x update?) Can we get a FAQ entry on the topic? Bonus points for an example user implementation. Thanks for your answer and for a great library! Jarom From: Hdf-forum [mailto:[email protected]] On Behalf Of Barbara Jones Sent: Tuesday, February 21, 2017 1:24 PM To: HDF Users Discussion List <[email protected]<mailto:[email protected]>> Subject: Re: [Hdf-forum] Complex numbers (1.10.x update?) Hi Jarom, We did originally plan to add support for complex types in HDF5-1.10. However, after the issue was examined closely, we decided to wait until we had a well-defined scope of what it means to add support for complex types within the library. The issue is still open but not assigned to be fixed in a specific release. -Barbara From: Hdf-forum [mailto:[email protected]] On Behalf Of Nelson, Jarom Sent: Thursday, February 09, 2017 10:32 AM To: [email protected]<mailto:[email protected]> Subject: [Hdf-forum] Complex numbers (1.10.x update?) At what point (if any?) will HDF5 support a complex floating point datatype (i.e. pair of real and imaginary floating point numbers) "out-of-the-box"? This is probably something that comes up frequently, but I haven't found the current status of the question. Searching the archives and the documentation, it seems that a complex floating point data type was at one point planned for the 1.10 release, however, I don't see anything about continuation of that plan in the documentation. Ref: these two threads from 2010 https://lists.hdfgroup.org/pipermail/hdf-forum_lists.hdfgroup.org/2010-December/004011.html https://lists.hdfgroup.org/pipermail/hdf-forum_lists.hdfgroup.org/2010-April/003049.html Perhaps the answer can be implied from this point in that thread: To be fair, because there's no one-size-fits-all complex number solution outside Fortran, a one-size-fits-all cross-language HDF5 helper method to define a complex type would be difficult to get right. Not technically difficult, just socially difficult. - Rhys Also, this seems like a likely topic for a FAQ. (There's one there for boolean datatype) Jarom Nelson, LLNL
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