Contents
zhptri - compute the inverse of a complex Hermitian indefin-
ite matrix A in packed storage using the factorization A =
U*D*U**H or A = L*D*L**H computed by ZHPTRF
SUBROUTINE ZHPTRI(UPLO, N, A, IPIVOT, WORK, INFO)
CHARACTER * 1 UPLO
DOUBLE COMPLEX A(*), WORK(*)
INTEGER N, INFO
INTEGER IPIVOT(*)
SUBROUTINE ZHPTRI_64(UPLO, N, A, IPIVOT, WORK, INFO)
CHARACTER * 1 UPLO
DOUBLE COMPLEX A(*), WORK(*)
INTEGER*8 N, INFO
INTEGER*8 IPIVOT(*)
F95 INTERFACE
SUBROUTINE HPTRI(UPLO, [N], A, IPIVOT, [WORK], [INFO])
CHARACTER(LEN=1) :: UPLO
COMPLEX(8), DIMENSION(:) :: A, WORK
INTEGER :: N, INFO
INTEGER, DIMENSION(:) :: IPIVOT
SUBROUTINE HPTRI_64(UPLO, [N], A, IPIVOT, [WORK], [INFO])
CHARACTER(LEN=1) :: UPLO
COMPLEX(8), DIMENSION(:) :: A, WORK
INTEGER(8) :: N, INFO
INTEGER(8), DIMENSION(:) :: IPIVOT
C INTERFACE
#include <sunperf.h>
void zhptri(char uplo, int n, doublecomplex *a, int *ipivot,
int *info);
void zhptri_64(char uplo, long n, doublecomplex *a, long
*ipivot, long *info);
zhptri computes the inverse of a complex Hermitian
indefinite matrix A in packed storage using the factoriza-
tion A = U*D*U**H or A = L*D*L**H computed by ZHPTRF.
UPLO (input)
Specifies whether the details of the factorization
are stored as an upper or lower triangular matrix.
= 'U': Upper triangular, form is A = U*D*U**H;
= 'L': Lower triangular, form is A = L*D*L**H.
N (input) The order of the matrix A. N >= 0.
A (input/output) COMPLEX*16 array, dimension (N*(N+1)/2)
On entry, the block diagonal matrix D and the mul-
tipliers used to obtain the factor U or L as com-
puted by ZHPTRF, stored as a packed triangular
matrix.
On exit, if INFO = 0, the (Hermitian) inverse of
the original matrix, stored as a packed triangular
matrix. The j-th column of inv(A) is stored in the
array A as follows: if UPLO = 'U', A(i + (j-
1)*j/2) = inv(A)(i,j) for 1<=i<=j; if UPLO = 'L',
A(i + (j-1)*(2n-j)/2) = inv(A)(i,j) for j<=i<=n.
IPIVOT (input) INTEGER array, dimension (N)
Details of the interchanges and the block struc-
ture of D as determined by ZHPTRF.
WORK (workspace)
COMPLEX*16 array, dimension(N)
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an ille-
gal value
> 0: if INFO = i, D(i,i) = 0; the matrix is singu-
lar and its inverse could not be computed.