code: public static void constraintMatrix6x3( DMatrixRMaj L_6x10 , DMatrixRMaj L_6x3 ) {
  
  		int index = 0;
  		for( int i = 0; i < 6; i++ ) {
  			L_6x3.data[index++] = L_6x10.get(i,0);
  			L_6x3.data[index++] = L_6x10.get(i,1);
  			L_6x3.data[index++] = L_6x10.get(i,4);
  		}
  	}
docs: Extracts the linear constraint matrix for case 2 from the full 6x10 constraint matrix.