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Map NetCDF API Syntax to MATLAB Syntax

MATLAB® netcdf package of low-level functions and its correspondence with the NetCDF C library.

MATLAB provides access to the routines in the NetCDF C library through a set of low-level functions that are grouped into a package called netcdf. Use the functions in this package to read and write data to and from NetCDF files. To use the MATLAB NetCDF functions effectively, you should be familiar with the NetCDF C interface.

Usually, the MATLAB functions in the netcdf package correspond directly to routines in the NetCDF C library. For example, the MATLAB function netcdf.open corresponds to the NetCDF library routine nc_open. In some cases, one MATLAB function corresponds to a group of NetCDF library functions. For example, instead of creating MATLAB versions of every NetCDF library nc_put_att_type function, where type represents a data type, MATLAB uses one function, netcdf.putAtt, to handle all supported data types.

To call one of the functions in the netcdf package, you must prefix the function name with the package name. The syntax of the MATLAB functions is similar to the NetCDF library routines. However, the NetCDF C library routines use input parameters to return data, while their MATLAB counterparts use one or more return values. For example, this is the function signature of the nc_open routine in the NetCDF library:

int nc_open (const char *path, int omode, int *ncidp); /* C syntax */

The NetCDF file identifier is returned in the ncidp argument.

This is the signature of the corresponding MATLAB function, netcdf.open:

ncid = netcdf.open(filename, mode)

Like its NetCDF C library counterpart, the MATLAB NetCDF function accepts a file name and a constant that specifies the access mode. However, that the MATLAB netcdf.open function returns the file identifier, ncid, as a return value.

The MATLAB NetCDF functions automatically choose the MATLAB class that best matches the NetCDF data type. This table shows the default mapping.

NetCDF Data TypeMATLAB Class
'NC_BYTE'int8 or uint8[a]
'NC_CHAR'char
'NC_SHORT'int16
'NC_INT'int32
'NC_FLOAT'single
'NC_DOUBLE'double

[a] NetCDF interprets byte data as either signed or unsigned.

You can override the default and specify the class of the return data by using an optional argument to the netcdf.getVar function.

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