How to properly use memory dynamically allocated in C++ dll within Matlab -

i wrote c++ interface dll call key image processing statistical measuring methods intel's integrated performance primitives (ipp) library can exploit simd capabilities. able pass 2 2d matlab arrays on function using calllib

a = single( rand(3,4) ); b = single( rand(3,2) );  pout = calllib('ippinterface', 'myfunc', a' , b' , size(a,1), size(a,2) , size(b,1), size(b,2) ); 

where in c++ myfunc has following signature, , snippet of body...

float* myfunc( float a[] , float b[] , int nrowsa , int ncolsa , int nrowsb , int ncolsb ) {     ...     float[] pdst = new float[nrowsa*ncolsa];     ...     return pdst; } 

what i'm unsure of how , if matlab deletes such buffers memory. wind in matlab process lib.pointers:

>> class(pout)  ans =  lib.pointer 

i'm curious if i'm doing bad idea, or if calling matlab's clear pout take care of , avoid conceivable memory leak.

so i've been doing memory testing creating in matlab 2 arrays follows...

i = single( rand( 1200 , 1600 ) ); t = single( rand( 100  , 100  ) ); 

i put function in loop printing of memory usage text file , clearing returned libpointer.

for = 1:10000     lp = calllib('ippinterface', 'myfunc', , t , size(i,2) , size(i,1) , size(t,2) , size(t,1) );     clear lp;      [u,s] = memory;      fprintf( fileid ,'%13g    %13s\n' ,  u.memusedmatlab , s.systemmemory.available ); end  

going route fills physical memory can see below, , has convinced me doing bad idea , matlab not handle in automated garbage collection fashion you.

>> memory maximum possible array:              38799 mb (4.068e+010 bytes) * memory available arrays:     38799 mb (4.068e+010 bytes) * memory used matlab:               21393 mb (2.243e+010 bytes) physical memory (ram):               34814 mb (3.650e+010 bytes)  *  limited system memory (physical + swap file) available. >> clear >> memory maximum possible array:              38803 mb (4.069e+010 bytes) * memory available arrays:     38803 mb (4.069e+010 bytes) * memory used matlab:               21388 mb (2.243e+010 bytes) physical memory (ram):               34814 mb (3.650e+010 bytes)  *  limited system memory (physical + swap file) available. >>  

if close matlab os naturally reclaims memory.

after digging around matlab's website did find close enough example whereby example had dynamically allocated c-struct in shared library, , later on matlab had call function written in same library sole task delete struct.

working pointer arguments; multilevel pointers

this example right on, after implementing simple interface call shared lib deallocate array , using after done

void deallocatearray( float* ) {     delete[] a; } 

the memory profile flat, , entire 10000 iterations complete more rapidly...

for = 1:10000     lp = calllib('ippinterface', 'myfunc', , t , size(i,2) , size(i,1) , size(t,2) , size(t,1) );     calllib('ippinterface', 'deallocatearray', lp );     clear lp;      [u,s] = memory;      fprintf( fileid ,'%13g    %13s\n' ,  u.memusedmatlab , s.systemmemory.available ); end