31. Where I is the 3 x 3 identity matrix and \ boldsymbol \ tau is the deviatoric stress tensor. 32. This time there is a 2 ?2 identity matrix pre-multiplying the energy operator conventionally not written. 33. Throughout, " ? ij " is the Kronecker delta, the components of the identity matrix . 34. It follows that the determinant of the identity matrix is 1 and the trace is " n ". 35. If this matrix were the identity matrix , then the flavor eigenstates would be the same as the mass eigenstates. 36. Indices are " raised " or " lowered " by multiplication by an appropriate matrix, often the identity matrix . 37. Now it is straightforward to verify closure, associativity, and inclusion of identity ( the identity matrix ) and inverses. 38. A "'scalar matrix "'is a diagonal matrix which is a constant times the identity matrix . 39. The factors are determined up to the negative 4th-order identity matrix , i . e . the central inversion. 40. Here I is the identity matrix of the same dimension as A, and h is a real, positive number.
