User`s manual

2 Creating C Language MEX-Files

2-10

In the above example, scalars are viewed as 1-by-1 matrices. Alternatively, you

can use a special API function called

mxGetScalar that returns the values of

scalars instead of pointers to copies of scalar variables. This is the alternative

code (error checking has been omitted for brevity).

#include "mex.h"

* timestwoalt.c - example found in API guide

* Use mxGetScalar to return the values of scalars instead of

* pointers to copies of scalar variables.

* This is a MEX-file for MATLAB.

/* $Revision: 1.5 $ */

void timestwo_alt(double *y, double x)

{

*y = 2.0*x;

}

void mexFunction( int nlhs, mxArray *plhs[],

int nrhs, const mxArray *prhs[] )

{

double *y;

double x;

/* Create a 1-by-1 matrix for the return argument. */

plhs[0] = mxCreateDoubleMatrix(1,1,mxREAL);

/* Get the scalar value of the input x. */

/* Note: mxGetScalar returns a value, not a pointer. */

x = mxGetScalar(prhs[0]);

/* Assign a pointer to the output. */

y = mxGetPr(plhs[0]);