External Interfaces |
Calling Functions from C MEX-Files
It is possible to call MATLAB functions, operators, M-files, and other MEX-files from within your C source code by using the API function mexCallMATLAB
. This example creates an mxArray
, passes various pointers to a subfunction to acquire data, and calls mexCallMATLAB
to calculate the sine function and plot the results.
/* * ============================================================= * sincall.c * * Example for illustrating how to use mexCallMATLAB * * Creates an mxArray and passes its associated pointers (in * this demo, only pointer to its real part, pointer to number of * rows, pointer to number of columns) to subfunction fill() to * get data filled up, then calls mexCallMATLAB to calculate sin * function and plot the result. * * This is a MEX-file for MATLAB. * Copyright (c) 1984-2000 The MathWorks, Inc. * ============================================================= */ /* $Revision: 1.4 $ */ #include "mex.h" #define MAX 1000 /* Subroutine for filling up data */ void fill(double *pr, int *pm, int *pn, int max) { int i; /* You can fill up to max elements, so (*pr) <= max. */ *pm = max/2; *pn = 1; for (i = 0; i < (*pm); i++) pr[i] = i * (4*3.14159/max); } /* The gateway routine */ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) { int m, n, max = MAX; mxArray *rhs[1], *lhs[1]; rhs[0] = mxCreateDoubleMatrix(max, 1, mxREAL); /* Pass the pointers and let fill() fill up data. */ fill(mxGetPr(rhs[0]), &m, &n, MAX); mxSetM(rhs[0], m); mxSetN(rhs[0], n); /* Get the sin wave and plot it. */ mexCallMATLAB(1, lhs, 1, rhs, "sin"); mexCallMATLAB(0, NULL, 1, lhs, "plot"); /* Clean up allocated memory. */ mxDestroyArray(rhs[0]); mxDestroyArray(lhs[0]); return; }
Note
It is possible to generate an object of type mxUNKNOWN_CLASS using mexCallMATLAB . See the example below.
|
The following example creates an M-file that returns two variables but only assigns one of them a value.
MATLAB displays the following warning message.
If you then call foo
using mexCallMATLAB
, the unassigned output variable will now be of type mxUNKNOWN_CLASS
.
Handling Sparse Arrays | Advanced Topics |
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