MATLAB Programming

7 Working with Scientific Data Formats
stat = hdfsd('endaccess',sds_id);
Step 6: Closing an HDF4 File. After writing data to a data set and closing
the data set, you must also close the HDF4 file. In the HDF4 SD API, you
use the SDend routine. In MATLAB, use the hdfsd function, specifying end
as the first argument. As the only other argument, specify a valid HDF4 SD
file identifier, sd_id in this example:
stat = hdfsd('end',sd_id);
You must close access to all the data sets in an HDF4 file before closing it.
Note Closing an HDF4 file executes all the write operations that have been
queued using SDwritedata. As a convenience, the MATLAB HDF Utility
API provides a function that can close all open data set and file identifiers
with a single call. See “Using the MATLAB HDF4 Utility API” on page 7-70
for more information.
Using the MATLAB HDF4 Utility API
In addition to the standard HDF4 APIs, listed in the hdfreference page,
MATLAB supports utility functions that are designed to make it easier to use
HDF4 in the MATLAB environment.
For example, using the gateway function to the MATLAB HDF4 utility API,
hdfml, and specifying the name of the listinfo routine as an argument, you
can view all the currently open HDF4 identifiers. MATLAB updates this list
whenever HDF identifiers are created or closed. In the following example
only two identifiers are open.
hdfml('listinfo')
No open RI identifiers
No open GR identifiers
No open grid identifiers
No open grid file identifiers
No open annotation identifiers
No open AN identifiers
Open scientific dataset identifiers:
262144
7-70