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C MEX-Files

C MEX-files are built by using the mex script to compile your C source code with additional calls to API routines.

The Components of a C MEX-File

The source code for a MEX-file consists of two distinct parts:

In the gateway routine, you can access the data in the mxArray structure and then manipulate this data in your C computational subroutine. For example, the expression mxGetPr(prhs[0]) returns a pointer of type double * to the real data in the mxArray pointed to by prhs[0]. You can then use this pointer like any other pointer of type double * in C. After calling your C computational routine from the gateway, you can set a pointer of type mxArray to the data it returns. MATLAB is then able to recognize the output from your computational routine as the output from the MEX-file.

The following C MEX Cycle figure shows how inputs enter a MEX-file, what functions the gateway routine performs, and how outputs return to MATLAB.

Figure: C MEX cycle

Figure 4-1: C MEX Cycle


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