How can I create a matrix of type uint32 using mxCreateNumericMatrix and fill it using memcpy() in MATLAB 7.6 (R2008a)?

I wasn't able to find any examples on how to create a non-double matrix. I would also like to fill it using the C function memcpy() to avoid a time consuming loop.

Answer 1

[MathWorks Support Team]

The following example demonstrates how to create an uint32 matrix and copy the data from a vector data structure (requires C++) using the memcpy() function.

// Name: uint32test.cpp

// Compile: mex uint32test.cpp

// Test: uint32test

#include "mex.h"

#include <stdio.h>

#include <stdlib.h>

#include <vector>

#define printf mexPrintf

/* Output Arguments */

#defineMY_OUTplhs[0]

#define MY_SIZE10

typedef unsigned int MY_TYPE; // Define data type (should match MATLAB type, e. g. mxUINT32_CLASS).

using std::vector; // C++.

// MEX-gateway routine.

void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {

      vector<MY_TYPE> testVector;

      testVector.reserve(MY_SIZE);

      // Fill test vector with numbers.

      MY_TYPE tempCounter = 0; // 0 to MY_SIZE.

      for (tempCounter = 0; tempCounter < MY_SIZE; ++tempCounter) {

          testVector.push_back(tempCounter);

      }

      // Create uint32 matrix of dimensions tempCounter * 4.

      MY_OUT = mxCreateNumericMatrix((mwSize) tempCounter, (mwSize) 4, mxUINT32_CLASS, mxREAL);

      // Use memcpy to fill the matrix instead of using a loop.

      MY_TYPE * ptr_OUT = (MY_TYPE *) mxGetPr(MY_OUT);

      // Each column is filled separately, but the whole matrix could also be filled at once,

      // if the copied data has the same size as the matrix.

      memcpy(&ptr_OUT[0], &testVector[0], tempCounter * sizeof(MY_TYPE)); // Column 1.

      memcpy(&ptr_OUT[tempCounter], &testVector[0], tempCounter * sizeof(MY_TYPE)); // Column 2.

      memcpy(&ptr_OUT[2 * tempCounter], &testVector[0], tempCounter * sizeof(MY_TYPE)); // Column 3.

      memcpy(&ptr_OUT[3 * tempCounter], &testVector[0], tempCounter * sizeof(MY_TYPE)); // Column 4.

      return;

}