ZHPGST reduces a complex Hermitian-definite generalized


 eigenproblem to standard form, using packed storage.


 If ITYPE = 1, the problem is A*x = lambda*B*x,


 and A is overwritten by inv(U**H)*A*inv(U) or inv(L)*A*inv(L**H)


 If ITYPE = 2 or 3, the problem is A*B*x = lambda*x or


 B*A*x = lambda*x, and A is overwritten by U*A*U**H or L**H*A*L.


 B must have been previously factorized as U**H*U or L*L**H by ZPPTRF.

ITYPE

          ITYPE is INTEGER


          = 1: compute inv(U**H)*A*inv(U) or inv(L)*A*inv(L**H);


          = 2 or 3: compute U*A*U**H or L**H*A*L.

UPLO

          UPLO is CHARACTER*1


          = 'U':  Upper triangle of A is stored and B is factored as


                  U**H*U;


          = 'L':  Lower triangle of A is stored and B is factored as


                  L*L**H.

N

          N is INTEGER


          The order of the matrices A and B.  N >= 0.

AP

          AP is COMPLEX*16 array, dimension (N*(N+1)/2)


          On entry, the upper or lower triangle of the Hermitian matrix


          A, packed columnwise in a linear array.  The j-th column of A


          is stored in the array AP as follows:


          if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;


          if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.


          On exit, if INFO = 0, the transformed matrix, stored in the


          same format as A.

BP

          BP is COMPLEX*16 array, dimension (N*(N+1)/2)


          The triangular factor from the Cholesky factorization of B,


          stored in the same format as A, as returned by ZPPTRF.

INFO

          INFO is INTEGER


          = 0:  successful exit


          < 0:  if INFO = -i, the i-th argument had an illegal value

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

November 2011