External Interfaces

Data Conversion

This section contains information on how MATLAB handles conversion of argument data and how to convert data yourself when you decide that would be more efficient.

Under most conditions, data passed to and from external library functions is automatically converted by MATLAB to the data type expected by the external function. However, you may choose, at times, to convert some of your argument data manually. Circumstances under which you might find this advantageous are

• When you pass the same piece of data to a series of library functions, it probably makes more sense to convert it once manually at the start rather than having MATLAB convert it automatically on every call. This saves time on unnecessary copy and conversion operations.
• When you pass large structures, you can save memory by creating MATLAB structures that match the shape of the C structures used in the external function instead of using generic MATLAB structures. The libstruct function creates a MATLAB structure modeled from a C structure taken from the library.
• When an argument to an external function uses more than one level of referencing (e.g., double **), you will need to pass a reference (constructed by the libpointer function) rather than have MATLAB convert the data type automatically.

Passing References

Primitive Types

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