memory management - Modifying a large dynamically sized 3D array mex/C++ -

short story: trying modify large 3d array gets allocated @ run-time on heap. believe function modifies array, vcross shown below, creating memory doesn't destroyed.

---

longer story: have large 3d double array (~126000x3x3 or 8.6mb) need run operations on. don't know how large first dimension of array @ compile time, allocate memory heap using new , delete operations.

when try store values array, segmentation violation. makes me think while storing values array, i'm creating memory somewhere goes waste, , fills heap.

the code compiles fine, hits seg violation when run it.

static void inpolyh(     double (*f)[3],//pointer array[3], treated 2d array don't know first dimension until run-time.     double (*v)[3],     double (*p)[3],     size_t numf,     size_t nump) {      /*calculate basenormals*/     //allocate memory on heap     double (*basenormals)[3] = null;//pointer array[3]     if ( !(basenormals = new double[numf][3]) ) { out_of_memory(); }      //store vector cross products in each array[3] of basenormals     (int i=0; i<numf; i++) {          vcross(basenormals[i],              v[(int)f[i][0]],              v[(int)f[i][1]],              v[(int)f[i][2]]);          //this works     }      /*calculate face normals of tetrahedron*/     //allocate memory on heap (this works)     double (*facenormals)[3][3] = null; //pointer array[3] of arrays[3]     if ( !(facenormals = new double[nump][3][3]) ) { out_of_memory(); }      //store vector cross products each array[3] of facenormals     (int i=0; i<nump; i++ ) {         (int j=0; j<3; j++ ) {             vcross(facenormals[i][j],                 p[i],                 v[ (int) f[i][j] ],                 v[ (int) f[i][ (j + 1) % 3 ] ] );             //seg violation @ i=37560         }     }      delete [] basenormals;     delete [] facenormals; } 

this believe culprit be. think function creates memory somewhere never gets destroyed. vector cross product functions accepts 4 array[3] parameters , assigns values first input parameter, passed reference.

static void vcross(     double (&n)[3],     double a[3],     double b[3],     double c[3]) {     n[0] = b[1] * c[2] - a[1] * c[2] + a[1] * b[2] - b[2]                 * c[1] + a[2] * c[1] - a[2] * b[1];     n[1] = b[2] * c[0] - a[2] * c[0] + a[2] * b[0] - b[0]                 * c[2] + a[0] * c[2] - a[0] * b[2];     n[2] = b[0] * c[1] - a[0] * c[1] + a[0] * b[1] - b[1]                 * c[0] + a[1] * c[0] - a[1] * b[0];     return; } 

other details may matter:

• this intended mex function run in matlab.
• default encoding: windows-1252
• matlab root : c:\program files\matlab\r2012b
• matlab version : 8.0.0.783 (r2012b)
• operating system: microsoft windows 7
• processor id : x86 family 6 model 58 stepping 9, genuineintel
• virtual machine : java 1.6.0_17-b04 sun microsystems inc. java hotspot(tm) 64-bit server vm mixed mode
• window system : version 6.1 (build 7601: service pack 1)

are sure (int)f[i][j] in range [0, <dimension of v>)? first thing i'd print out values of (int)f[i][j] when loop runs. or fire debugger see values @ moment of crash.