h5write — Write dense numeric, logical, string, or char data to an HDF5 dataset.
h5write(filename, dataset, data) creates or replaces a dense HDF5 dataset, creating intermediate groups as needed. h5write(filename, dataset, data, start, count) and h5write(filename, dataset, data, start, count, stride) write one-based hyperslab selections into an existing dataset.
Syntax
h5write(filename, dataset, data)How h5write works
- Numeric data is written as double, logical data as HDF5 booleans, and string/char data as UTF-8 variable-length strings.
- RunMat column-major arrays are converted to HDF5 row-major raw order while preserving visible dimensions.
- Partial writes use native HDF5 hyperslab writes and require the data shape to match the selected
count. - Sparse, complex, cell, struct, object, and handle values raise deterministic unsupported-type errors.
Example
Write a matrix
h5write('out.h5', '/A', magic(3));Using h5write with coding agents
Open a RunMat example with live inputs, then ask the agent to explain how h5write changes the result.
Run a small h5write example, explain the result, then change one input and compare the output.
Related Io functions
Repl Fs
addpath · cd · copyfile · delete · dir · exist · fileattrib · fileparts · fullfile · genpath · getenv · getpref · isenv · isfile · isfolder · ispref · ls · matlabroot · memmapfile · mkdir · movefile · open · opentoline · path · pathsep · pcode · pwd · readstruct · rehash · restoredefaultpath · rmdir · rmpath · run · savepath · setenv · setpref · system · tempdir · tempname · uigetdir · uigetfile · uiputfile · unsetenv · userpath · what · winqueryreg · xmlread · xmlwrite
Tabular
arrayDatastore · csvread · csvwrite · detectImportOptions · dlmread · dlmwrite · fileDatastore · parquetDatastore · parquetinfo · parquetread · readcell · readmatrix · readtable · readtimetable · spreadsheetImportOptions · writecell · writematrix · writetable · writetimetable · xlsread · xlswrite
Filetext
fclose · feof · fgetl · fgets · fileread · filewrite · fopen · fprintf · fread · frewind · fwrite · readlines · writelines
Import
Json
Open-source implementation
Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how h5write is executed, line by line, in Rust.
- View the source for h5write in Rust on GitHub
- Learn how the RunMat runtime works
- Found a bug? Open an issue with a minimal reproduction.
About RunMat
RunMat is an open-source runtime that executes MATLAB-syntax code blazing on any GPU. It is licensed under the Apache 2.0 license.
- RunMat automatically optimizes your math for GPU execution on Apple, Nvidia, and AMD hardware. No code changes needed. Simulations that took hours now take minutes.
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