csptri()

subroutine csptri	(	character	uplo,
		integer	n,
		complex, dimension( * )	ap,
		integer, dimension( * )	ipiv,
		complex, dimension( * )	work,
		integer	info )

CSPTRI

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Purpose:

!>
!> CSPTRI computes the inverse of a complex symmetric indefinite matrix
!> A in packed storage using the factorization A = U*D*U**T or
!> A = L*D*L**T computed by CSPTRF.
!> 

Parameters

[in]	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**T; !> = 'L': Lower triangular, form is A = L*D*L**T. !>
[in]	N	!> N is INTEGER !> The order of the matrix A. N >= 0. !>
[in,out]	AP	!> AP is COMPLEX 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 CSPTRF, !> stored as a packed triangular matrix. !> !> On exit, if INFO = 0, the (symmetric) 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. !>
[in]	IPIV	!> IPIV is INTEGER array, dimension (N) !> Details of the interchanges and the block structure of D !> as determined by CSPTRF. !>
[out]	WORK	!> WORK is COMPLEX array, dimension (N) !>
[out]	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

Univ. of Colorado Denver

NAG Ltd.