# zhptri.f(3) [centos man page]

```zhptri.f(3)							      LAPACK							       zhptri.f(3)

NAME
zhptri.f -

SYNOPSIS
Functions/Subroutines
subroutine zhptri (UPLO, N, AP, IPIV, WORK, INFO)
ZHPTRI

Function/Subroutine Documentation
subroutine zhptri (characterUPLO, integerN, complex*16, dimension( * )AP, integer, dimension( * )IPIV, complex*16, dimension( * )WORK,
integerINFO)
ZHPTRI

Purpose:

ZHPTRI computes the inverse of a complex Hermitian indefinite matrix
A in packed storage using the factorization A = U*D*U**H or
A = L*D*L**H computed by ZHPTRF.

Parameters:
UPLO

UPLO is CHARACTER*1
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

N is INTEGER
The order of the matrix A.  N >= 0.

AP

AP is COMPLEX*16 array, dimension (N*(N+1)/2)
On entry, the block diagonal matrix D and the multipliers
used to obtain the factor U or L as computed 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 AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = inv(A)(i,j) for 1<=i<=j;
if UPLO = 'L',
AP(i + (j-1)*(2n-j)/2) = inv(A)(i,j) for j<=i<=n.

IPIV

IPIV is INTEGER array, dimension (N)
Details of the interchanges and the block structure of D
as determined by ZHPTRF.

WORK

WORK is COMPLEX*16 array, dimension (N)

INFO

INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, D(i,i) = 0; the matrix is singular and its
inverse could not be computed.

Author:
Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Date:
November 2011

Definition at line 110 of file zhptri.f.

Author
Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						       zhptri.f(3)```

## Check Out this Related Man Page

```ZHPTRI(l)								 )								 ZHPTRI(l)

NAME
ZHPTRI  -  compute  the	inverse  of  a complex Hermitian indefinite matrix A in packed storage using the factorization A = U*D*U**H or A =
L*D*L**H computed by ZHPTRF

SYNOPSIS
SUBROUTINE ZHPTRI( UPLO, N, AP, IPIV, WORK, INFO )

CHARACTER	  UPLO

INTEGER	  INFO, N

INTEGER	  IPIV( * )

COMPLEX*16	  AP( * ), WORK( * )

PURPOSE
ZHPTRI computes the inverse of a complex Hermitian indefinite matrix A in packed storage using the  factorization  A  =	U*D*U**H  or  A  =
L*D*L**H computed by ZHPTRF.

ARGUMENTS
UPLO    (input) CHARACTER*1
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) INTEGER
The order of the matrix A.  N >= 0.

AP      (input/output) COMPLEX*16 array, dimension (N*(N+1)/2)
On entry, the block diagonal matrix D and the multipliers used to obtain the factor U or L as  computed	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 AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = inv(A)(i,j) for 1<=i<=j; if  UPLO  =  'L',  AP(i  +
(j-1)*(2n-j)/2) = inv(A)(i,j) for j<=i<=n.

IPIV    (input) INTEGER array, dimension (N)
Details of the interchanges and the block structure of D as determined by ZHPTRF.

WORK    (workspace) COMPLEX*16 array, dimension (N)

INFO    (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, D(i,i) = 0; the matrix is singular and its inverse could not be computed.

LAPACK version 3.0						   15 June 2000 							 ZHPTRI(l)```
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