code: public IMatrix getIz() {
          IMatrix Iz = new IMatrix(size, size);
          int i, j;
          for (i = 0; i < size; i++)
              for (j = 0; j < size; j++) {
                  Iz.realmatrix[i][j] = 0d;
                  Iz.imagmatrix[i][j] = 0d;
              }
          for (i = 0; i < size; i++) {
              Iz.realmatrix[i][i] = J - i;
              Iz.imagmatrix[i][i] = J - i;
          }
          return Iz;
      }
docs: Calculates the Iz operator