mexFunction (External Interfaces Reference)

Entry point to C MEX-file

C Syntax

#include "mex.h"
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, 
     const mxArray *prhs[]);

Arguments

nlhs
MATLAB sets nlhs with the number of expected mxArrays.

plhs
MATLAB sets plhs to a pointer to an array of NULL pointers.

nrhs
MATLAB sets nrhs to the number of input mxArrays.

prhs
MATLAB sets prhs to a pointer to an array of input mxArrays. These mxArrays are declared as constant; they are read only and should not be modified by your MEX-file. Changing the data in these mxArrays may produce undesired side effects.

Description

mexFunction is not a routine you call. Rather, mexFunction is the generic name of the function entry point that must exist in every C source MEX-file. When you invoke a MEX-function, MATLAB finds and loads the corresponding MEX-file of the same name. MATLAB then searches for a symbol named mexFunction within the MEX-file. If it finds one, it calls the MEX-function using the address of the mexFunction symbol. If MATLAB cannot find a routine named mexFunction inside the MEX-file, it issues an error message.

When you invoke a MEX-file, MATLAB automatically seeds nlhs, plhs, nrhs, and prhs with the caller's information. In the syntax of the MATLAB language, functions have the general form

```
[a,b,c,...] = fun(d,e,f,...)
```

where the ... denotes more items of the same format. The a,b,c... are left-hand side arguments and the d,e,f... are right-hand side arguments. The arguments nlhs and nrhs contain the number of left-hand side and right-hand side arguments, respectively, with which the MEX-function is called. prhs is a pointer to a length nrhs array of pointers to the right-hand side mxArrays. plhs is a pointer to a length nlhs array where your C function must put pointers for the returned left-hand side mxArrays.

Examples

See mexfunction.c in the mex subdirectory of the examples directory.

mexEvalString mexFunctionName