NAME

zhpgst - reduce a complex Hermitian-definite generalized eigenproblem to standard form, using packed storage

SYNOPSIS

  SUBROUTINE ZHPGST( ITYPE, UPLO, N, AP, BP, INFO)
  CHARACTER * 1 UPLO
  DOUBLE COMPLEX AP(*), BP(*)
  INTEGER ITYPE, N, INFO

  SUBROUTINE ZHPGST_64( ITYPE, UPLO, N, AP, BP, INFO)
  CHARACTER * 1 UPLO
  DOUBLE COMPLEX AP(*), BP(*)
  INTEGER*8 ITYPE, N, INFO

  SUBROUTINE HPGST( ITYPE, UPLO, N, AP, BP, [INFO])
  CHARACTER(LEN=1) :: UPLO
  COMPLEX(8), DIMENSION(:) :: AP, BP
  INTEGER :: ITYPE, N, INFO

  SUBROUTINE HPGST_64( ITYPE, UPLO, N, AP, BP, [INFO])
  CHARACTER(LEN=1) :: UPLO
  COMPLEX(8), DIMENSION(:) :: AP, BP
  INTEGER(8) :: ITYPE, N, INFO

#include <sunperf.h>

void zhpgst(int itype, char uplo, int n, doublecomplex *ap, doublecomplex *bp, int *info);

void zhpgst_64(long itype, char uplo, long n, doublecomplex *ap, doublecomplex *bp, long *info);

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 CPPTRF.

ITYPE (input)

 = 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 (input)

 = '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 (input)
The order of the matrices A and B. N > = 0.
AP (input/output)
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 (input)
The triangular factor from the Cholesky factorization of B, stored in the same format as A, as returned by CPPTRF.

INFO (output)

 = 0:  successful exit

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