Dynamically allocate a 2D matrix of ints

gistfile1.c

int **int_matrix_alloc(int n, int m){
	int *a, **aa, i;
	a = (int *)calloc(n * m, sizeof(int));
	aa = (int **)calloc(n, sizeof(int *));
	for(i=0;i<n;i++){
		aa[i] = &a[i * m];
	}
	return aa;
}