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Unit 27: Introduction and Forms on Inner Product Spaces




          27.4 Keywords                                                                         Notes

          A Sesquilinear Form: A sesquilinear form on a real or complex vector space V is a function f on
          V   V with values in the field of scalars such that

                 f(c + , ) = cf(, ) + f(, )
                 f( + c, ) = cf(, ) + f(, )
          for all  ,     in V and all scalars c.

          Hermitian: A form f on a real or complex vector space V is called Hermitian if
                 f(, ) =  ( , )f
          for all  and  in V.
          Self-adjoint: The  linear operator T is self-adjoint on a complex finite-dimensional inner product
          space V, if and only if (T|) is real for every  in V.

          27.5 Review Questions

          1.   Let
                    1  i
               A =
                    i  2
               and let g be the form (on the space of 2 × 1 complex matrices) defined by g(X, Y) = Y*AX.
               Is g an inner product?
          2.   Let f be the form on R  defined by
                                 2
               f [(x , y ), (y , y )] = x y  + x y
                  1  1  2  2   1 1  2 2
               Find the matrix of f in each of the following bases:
               {(1, –1), (1, 1)}, {(1, 2), (3, 4)}

          Answer: Self Assessment

          1.   (b), (c)

          27.6 Further Readings




           Books  Kenneth Hoffman and Ray Kunze, Linear Algebra

                 Michael Artin, Algebra

















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