# Uncategorized **URL:** https://forum.hdfgroup.org/c/uncategorized/1.md [Latest](https://forum.hdfgroup.org/latest.md) · [Categories](https://forum.hdfgroup.org/categories.md) --- ## [HDFql version 2.6.0](https://forum.hdfgroup.org/t/hdfql-version-2-6-0/13886)
**Author:** [@contact](https://forum.hdfgroup.org/u/contact)\ **Replies:** 0\ **Last updated:** [October 24, 2026, 8:44pm UTC](https://forum.hdfgroup.org/t/hdfql-version-2-6-0/13886 "2026-10-24T20:44:41Z")
We are happy to announce the release of HDFql 2.6.0! This version includes: Added wrapper for MATLAB Added support for specifying the type of padding (i.e. null-terminated, null-padded, or space-padded) used in a … --- ## [New Java hdf5 library](https://forum.hdfgroup.org/t/new-java-hdf5-library/13882)
**Author:** [@karl.nicholas](https://forum.hdfgroup.org/u/karl.nicholas)\ **Replies:** 0\ **Last updated:** [October 1, 2026, 9:24am UTC](https://forum.hdfgroup.org/t/new-java-hdf5-library/13882 "2026-10-01T09:24:38Z")
Hi, I wrote a java hdf5 library a while back figured I should share in case it is of interest to anyone. It seems to be in good shape, I was able to read all the NASA Earth satellite HDF5 files for example. Please find a… --- ## [Netcdf complains about hdf5/2](https://forum.hdfgroup.org/t/netcdf-complains-about-hdf5-2/13852)
**Author:** [@eijkhout](https://forum.hdfgroup.org/u/eijkhout)\ **Replies:** 5\ **Last updated:** [July 20, 2026, 7:50pm UTC](https://forum.hdfgroup.org/t/netcdf-complains-about-hdf5-2/13852 "2026-07-20T19:50:31Z")
I’m using essentially the same script for hdf5 version 1.14 and 2.whatever. But netcdf is happy with 1.14 and not with 2: -- Found HDF5: hdf5-shared (found version "2.0.0") found components: C HL -- Found HDF5 version: … --- ## [Does h5diff --exclude-attribute work on file level attrbutes?](https://forum.hdfgroup.org/t/does-h5diff-exclude-attribute-work-on-file-level-attrbutes/13731)
**Author:** [@daniel.a.kahn](https://forum.hdfgroup.org/u/daniel.a.kahn)\ **Replies:** 3\ **Last updated:** [April 8, 2026, 11:26am UTC](https://forum.hdfgroup.org/t/does-h5diff-exclude-attribute-work-on-file-level-attrbutes/13731 "2026-04-08T11:26:31Z")
Does –exclude-attribute in h5diff work on file (or root) level attributes? I’m not having much luck: \> h5diff --exclude-attribute ATTR File1.h5 File2.h5 attribute: \\> and \\> 3 differences found … --- ## [Installing MCNP for MAc](https://forum.hdfgroup.org/t/installing-mcnp-for-mac/13120)
**Author:** [@eruolagbenga](https://forum.hdfgroup.org/u/eruolagbenga)\ **Replies:** 1\ **Last updated:** [March 23, 2025, 6:11pm UTC](https://forum.hdfgroup.org/t/installing-mcnp-for-mac/13120 "2025-03-23T18:11:33Z")
Please kindly assist with the step by step installation process for MAC os --- ## [i cannot login in](https://forum.hdfgroup.org/t/i-cannot-login-in/13077)
**Author:** [@suiweikang](https://forum.hdfgroup.org/u/suiweikang)\ **Replies:** 1\ **Last updated:** [February 24, 2025, 9:22pm UTC](https://forum.hdfgroup.org/t/i-cannot-login-in/13077 "2025-02-24T21:22:26Z")
When i try to login in, i have registrated. There was a problem with your log in: Error exchanging code \[error code: unknown\] --- ## [File Format Conversion and compression](https://forum.hdfgroup.org/t/file-format-conversion-and-compression/11889)
**Author:** [@hana](https://forum.hdfgroup.org/u/hana)\ **Replies:** 0\ **Last updated:** [December 26, 2023, 7:47am UTC](https://forum.hdfgroup.org/t/file-format-conversion-and-compression/11889 "2023-12-26T07:47:40Z")
Transforming images from one format to another is fundamental. Different formats offer distinct advantages in terms of quality, compression, and transparency. I got a tif file image which is size in 8MB, the picture take… --- ## [Many links broken or wrong on download-related pages](https://forum.hdfgroup.org/t/many-links-broken-or-wrong-on-download-related-pages/11755)
**Author:** [@hdf51](https://forum.hdfgroup.org/u/hdf51)\ **Replies:** 1\ **Last updated:** [November 28, 2023, 6:04pm UTC](https://forum.hdfgroup.org/t/many-links-broken-or-wrong-on-download-related-pages/11755 "2023-11-28T18:04:46Z")
I noticed several problems with links in and around the download pages: On https://www.hdfgroup.org/downloads/hdf5, basically all links for additional information except the direct download links lead to a “404 - File … --- ## [Reading attributes with compound datatypes without a priori creating structs using C](https://forum.hdfgroup.org/t/reading-attributes-with-compound-datatypes-without-a-priori-creating-structs-using-c/11509)
**Author:** [@raffayatiq2341](https://forum.hdfgroup.org/u/raffayatiq2341)\ **Replies:** 1\ **Last updated:** [September 8, 2023, 9:38am UTC](https://forum.hdfgroup.org/t/reading-attributes-with-compound-datatypes-without-a-priori-creating-structs-using-c/11509 "2023-09-08T09:38:19Z")
Hello. I want to read attributes with compound datatypes without having to create a struct because my file contains many different compound datatypes and creating structs will be infeasible. I believe this is possible be… --- ## [HDFql version 2.5.0](https://forum.hdfgroup.org/t/hdfql-version-2-5-0/11502)
**Author:** [@contact](https://forum.hdfgroup.org/u/contact)\ **Replies:** 0\ **Last updated:** [September 5, 2023, 5:19am UTC](https://forum.hdfgroup.org/t/hdfql-version-2-5-0/11502 "2023-09-05T05:19:42Z")
We are happy to announce the release of HDFql 2.5.0! This version includes: Added support for sliding cursors (to enable reading a dataset that does not fit in (RAM) memory in a sliding fashion through a cursor, allo… --- ## [H5DWrite failure for large parallel file](https://forum.hdfgroup.org/t/h5dwrite-failure-for-large-parallel-file/11496)
**Author:** [@a.jackson](https://forum.hdfgroup.org/u/a.jackson)\ **Replies:** 0\ **Last updated:** [September 1, 2023, 2:04pm UTC](https://forum.hdfgroup.org/t/h5dwrite-failure-for-large-parallel-file/11496 "2023-09-01T14:04:22Z")
I’m using HDF5 1.10.6 on a HPE Cray system and when running at scale I get H5Dwrite failures with the following signature: HDF5-DIAG: Error detected in HDF5 (1.10.6) MPI-process 16407: #000: H5Dio.c line 336 in H5Dwrit… --- ## [Needs clarification : stride in HDF](https://forum.hdfgroup.org/t/needs-clarification-stride-in-hdf/11420)
**Author:** [@pierre](https://forum.hdfgroup.org/u/pierre)\ **Replies:** 8\ **Last updated:** [August 20, 2023, 4:57pm UTC](https://forum.hdfgroup.org/t/needs-clarification-stride-in-hdf/11420 "2023-08-20T16:57:37Z")
If I have a non-contiguous 2D memory buffer (with stride), I think that I can only write it to a data set by using stride values in hyperslabs. However, it can only work if the original stride (usually in bytes in API l… --- ## [Missing mod file h5se when building with cmake](https://forum.hdfgroup.org/t/missing-mod-file-h5se-when-building-with-cmake/11395)
**Author:** [@alain.miniussi](https://forum.hdfgroup.org/u/alain.miniussi)\ **Replies:** 1\ **Last updated:** [August 17, 2023, 8:40pm UTC](https://forum.hdfgroup.org/t/missing-mod-file-h5se-when-building-with-cmake/11395 "2023-08-17T20:40:11Z")
Hi, In fortran/src/CMakeLists.txt, in the module list files (modsh\_files, mod\_files), h5se.mod is missing. As a result, theyr’re not installed, yet it is referenced in hdf5 module. This is preventing at least some com… --- ## [Creating DLL to use H5 functions](https://forum.hdfgroup.org/t/creating-dll-to-use-h5-functions/11391)
**Author:** [@clu](https://forum.hdfgroup.org/u/clu)\ **Replies:** 1\ **Last updated:** [August 4, 2023, 1:24pm UTC](https://forum.hdfgroup.org/t/creating-dll-to-use-h5-functions/11391 "2023-08-04T13:24:52Z")
Hello! I’m currently trying to write a DLL that will be used to write data from some external sources into H5 files. I’m doing this in Visual Studio so I followed the instructions from “USING\_HDF5\_VS” (also attached), b… --- ## [CMake Error. MPI HDF5 build required. dolfinx](https://forum.hdfgroup.org/t/cmake-error-mpi-hdf5-build-required-dolfinx/11233)
**Author:** [@philliprusso](https://forum.hdfgroup.org/u/philliprusso)\ **Replies:** 2\ **Last updated:** [July 25, 2023, 2:59pm UTC](https://forum.hdfgroup.org/t/cmake-error-mpi-hdf5-build-required-dolfinx/11233 "2023-07-25T14:59:40Z")
when using cmake … for dolfinx package I have: CMake Error at CMakeLists.txt:238 (message): Found serial HDF5 build, MPI HDF5 build required, try setting HDF5\_DIR or HDF5\_ROOT prusso@cname:/usr/local/HDF\_Group/HDF5/1… --- ## [H5dump: displays wrong value for IEEE 754 quadruple precision value](https://forum.hdfgroup.org/t/h5dump-displays-wrong-value-for-ieee-754-quadruple-precision-value/11330)
**Author:** [@apollo3zehn-h5](https://forum.hdfgroup.org/u/apollo3zehn-h5)\ **Replies:** 1\ **Last updated:** [July 18, 2023, 6:16pm UTC](https://forum.hdfgroup.org/t/h5dump-displays-wrong-value-for-ieee-754-quadruple-precision-value/11330 "2023-07-18T18:16:47Z")
Edit: Please see my second post below, I had wrong assumptions about C#'s decimal type. I try to write a quadruple precision value ( = 128 bit floating point number, IEEE 754 - Wikipedia) using C# to an H5 file and then… --- ## [HDF5-DIAG: Error detected in HDF5 (1.10.7) thread 1:](https://forum.hdfgroup.org/t/hdf5-diag-error-detected-in-hdf5-1-10-7-thread-1/11293)
**Author:** [@farsad.heidari](https://forum.hdfgroup.org/u/farsad.heidari)\ **Replies:** 0\ **Last updated:** [July 10, 2023, 1:19pm UTC](https://forum.hdfgroup.org/t/hdf5-diag-error-detected-in-hdf5-1-10-7-thread-1/11293 "2023-07-10T13:19:56Z")
Dear experts, I try to use a basic project of Transmittance Spectrum of a Waveguide but I always get the following error: Main code: :point\_down: ; From the Meep tutorial: transmission around a 90-degree waveguide ; be… --- ## [VFD and Direct Chunk API](https://forum.hdfgroup.org/t/vfd-and-direct-chunk-api/11281)
**Author:** [@samuel.debionne](https://forum.hdfgroup.org/u/samuel.debionne)\ **Replies:** 1\ **Last updated:** [July 7, 2023, 5:18pm UTC](https://forum.hdfgroup.org/t/vfd-and-direct-chunk-api/11281 "2023-07-07T17:18:34Z")
Hello, It’s not clear to me where the VFD layer stands regarding the direct chunk API. Can I use H5Dread/write\_chunk() while using a VFD (such as the GDS one, in which case the const void \* buf would be interpreted as d… --- ## [Could you recommend Java library for reading/writing HDF5](https://forum.hdfgroup.org/t/could-you-recommend-java-library-for-reading-writing-hdf5/11280)
**Author:** [@jeliazkova.nina](https://forum.hdfgroup.org/u/jeliazkova.nina)\ **Replies:** 1\ **Last updated:** [July 6, 2023, 5:39pm UTC](https://forum.hdfgroup.org/t/could-you-recommend-java-library-for-reading-writing-hdf5/11280 "2023-07-06T17:39:54Z")
Could you recommend Java library for reading/writing HDF5. Ideally, with Maven distribution Thanks --- ## [Compiling HDF5 with Plugins (LZF)](https://forum.hdfgroup.org/t/compiling-hdf5-with-plugins-lzf/11223)
**Author:** [@mike.jackson](https://forum.hdfgroup.org/u/mike.jackson)\ **Replies:** 1\ **Last updated:** [June 22, 2023, 9:42pm UTC](https://forum.hdfgroup.org/t/compiling-hdf5-with-plugins-lzf/11223 "2023-06-22T21:42:38Z")
I’m a bit confused here. Do I compile HDF5 FIRST then the Plugin? Or compile the PLUGIN alongside HDF5? I’m looking for something in the HDF5 CMake codes to just tell HDF5 “I want these additional filters and this is wh… --- ## [ChatGPT as a forum assistant](https://forum.hdfgroup.org/t/chatgpt-as-a-forum-assistant/10616)
**Author:** [@lucasvr](https://forum.hdfgroup.org/u/lucasvr)\ **Replies:** 10\ **Last updated:** [March 27, 2023, 4:10pm UTC](https://forum.hdfgroup.org/t/chatgpt-as-a-forum-assistant/10616 "2023-03-27T16:10:14Z")
Hi, folks! Just like many of you, I have been playing around with ChatGPT and decided to see how well it would perform as a first-responder to new questions posted to the forum. Given the amount of HDF5-related documenta… --- ## [How to change my email address?](https://forum.hdfgroup.org/t/how-to-change-my-email-address/10347)
**Author:** [@philip.lee](https://forum.hdfgroup.org/u/philip.lee)\ **Replies:** 1\ **Last updated:** [October 31, 2022, 8:24pm UTC](https://forum.hdfgroup.org/t/how-to-change-my-email-address/10347 "2022-10-31T20:24:36Z")
I’ve noticed another post with the same question - and no answer after 2 years. How do I change the email address I used to register with the HDF group and this forum? I’m leaving my current job and need to change it. … --- ## [Strange links in blog post](https://forum.hdfgroup.org/t/strange-links-in-blog-post/10337)
**Author:** [@kittisopikulm](https://forum.hdfgroup.org/u/kittisopikulm)\ **Replies:** 1\ **Last updated:** [October 24, 2022, 9:49pm UTC](https://forum.hdfgroup.org/t/strange-links-in-blog-post/10337 "2022-10-24T21:49:44Z")
I noticed there are some strange links in Arabic script in this blog post for @gheber: For example, see the blue text at the end of this screenshot: The link appear to advertise online gambling sites. --- ## [Can HDF5 for C++ and h5py for python Coexist](https://forum.hdfgroup.org/t/can-hdf5-for-c-and-h5py-for-python-coexist/9887)
**Author:** [@yeshwath.mylapalle](https://forum.hdfgroup.org/u/yeshwath.mylapalle)\ **Replies:** 1\ **Last updated:** [June 21, 2022, 2:30pm UTC](https://forum.hdfgroup.org/t/can-hdf5-for-c-and-h5py-for-python-coexist/9887 "2022-06-21T14:30:56Z")
Hi, I am using an application called FlightGear(Which is an opensource flight simulation software), the use case is, i have an python code which reads .h5 file as an input and process the prediction. The python code is … --- ## [H5Rdestroy when stored](https://forum.hdfgroup.org/t/h5rdestroy-when-stored/9860)
**Author:** [@simonbyrne](https://forum.hdfgroup.org/u/simonbyrne)\ **Replies:** 1\ **Last updated:** [June 14, 2022, 3:48pm UTC](https://forum.hdfgroup.org/t/h5rdestroy-when-stored/9860 "2022-06-14T15:48:19Z")
If a reference is stored as an attribute to an object, should H5Rdestroy still be called? --- ## [Survey on the usage of self-describing data formats](https://forum.hdfgroup.org/t/survey-on-the-usage-of-self-describing-data-formats/9762)
**Author:** [@kira.duwe](https://forum.hdfgroup.org/u/kira.duwe)\ **Replies:** 2\ **Last updated:** [May 16, 2022, 10:47am UTC](https://forum.hdfgroup.org/t/survey-on-the-usage-of-self-describing-data-formats/9762 "2022-05-16T10:47:26Z")
Hi everyone, for my PhD thesis I am conducting a small survey. It focuses mostly on the usage of self-describing data formats such as HDF5, NetCDF or ADIOS2 with a small section on post-processing and data access APIs. … --- ## [How to set the array size and value when creating new attribute](https://forum.hdfgroup.org/t/how-to-set-the-array-size-and-value-when-creating-new-attribute/9608)
**Author:** [@kang\_peng](https://forum.hdfgroup.org/u/kang_peng)\ **Replies:** 3\ **Last updated:** [April 5, 2022, 3:11pm UTC](https://forum.hdfgroup.org/t/how-to-set-the-array-size-and-value-when-creating-new-attribute/9608 "2022-04-05T15:11:25Z")
Hi all, I’m trying to set an attribute like this, but always failed. Could you tell me how to set the array size and value? Thanks, Peter --- ## [Why are there .err files next to test files in binary plugin download?](https://forum.hdfgroup.org/t/why-are-there-err-files-next-to-test-files-in-binary-plugin-download/9394)
**Author:** [@kittisopikulm](https://forum.hdfgroup.org/u/kittisopikulm)\ **Replies:** 2\ **Last updated:** [March 7, 2022, 1:45pm UTC](https://forum.hdfgroup.org/t/why-are-there-err-files-next-to-test-files-in-binary-plugin-download/9394 "2022-03-07T13:45:58Z")
I was taking a look at the binary plugin files that you can download from HDF Group, and I noticed they come with some test files under share/HDFPLExamples/example/testfiles. h5ex\_d\_blosc.ddl h5ex\_d\_blosc.err h5ex\_d\_blo… --- ## [Can Compound Dataset been compressed?](https://forum.hdfgroup.org/t/can-compound-dataset-been-compressed/9457)
**Author:** [@kli](https://forum.hdfgroup.org/u/kli)\ **Replies:** 2\ **Last updated:** [February 28, 2022, 4:11pm UTC](https://forum.hdfgroup.org/t/can-compound-dataset-been-compressed/9457 "2022-02-28T16:11:14Z")
Hi guys I am a newbie to H5, and I am using MATLAB to write a structure array into H5 using compound datatype My structure has 20 fields, and most fields are 1-D double arrays (20 x 1), and some fields each element co… --- ## [Multithreading in WebAssembly](https://forum.hdfgroup.org/t/multithreading-in-webassembly/6525)
**Author:** [@sh.sagheb98](https://forum.hdfgroup.org/u/sh.sagheb98)\ **Replies:** 1\ **Last updated:** [January 2, 2020, 2:25pm UTC](https://forum.hdfgroup.org/t/multithreading-in-webassembly/6525 "2020-01-02T14:25:41Z")
Hi, I will be grateful if you answer my question about WebAssembly multithreading. I want to implement a code with 2 thread (a main thread and a helper one), such that there is a global variable that is used as a count… [Next page](https://forum.hdfgroup.org/c/uncategorized/1.md?page=1)