table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/zpftri.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/zpftri.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/zpftri.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine ZPFTRI (transr, uplo, n, a, info)
ZPFTRI
Function/Subroutine Documentation¶
subroutine ZPFTRI (character transr, character uplo, integer n, complex*16, dimension( 0: * ) a, integer info)¶
ZPFTRI
Purpose:
!> !> ZPFTRI computes the inverse of a complex Hermitian positive definite !> matrix A using the Cholesky factorization A = U**H*U or A = L*L**H !> computed by ZPFTRF. !>
Parameters
TRANSR
!> TRANSR is CHARACTER*1 !> = 'N': The Normal TRANSR of RFP A is stored; !> = 'C': The Conjugate-transpose TRANSR of RFP A is stored. !>
UPLO
!> UPLO is CHARACTER*1 !> = 'U': Upper triangle of A is stored; !> = 'L': Lower triangle of A is stored. !>
N
!> N is INTEGER !> The order of the matrix A. N >= 0. !>
A
!> A is COMPLEX*16 array, dimension ( N*(N+1)/2 ); !> On entry, the Hermitian matrix A in RFP format. RFP format is !> described by TRANSR, UPLO, and N as follows: If TRANSR = 'N' !> then RFP A is (0:N,0:k-1) when N is even; k=N/2. RFP A is !> (0:N-1,0:k) when N is odd; k=N/2. IF TRANSR = 'C' then RFP is !> the Conjugate-transpose of RFP A as defined when !> TRANSR = 'N'. The contents of RFP A are defined by UPLO as !> follows: If UPLO = 'U' the RFP A contains the nt elements of !> upper packed A. If UPLO = 'L' the RFP A contains the elements !> of lower packed A. The LDA of RFP A is (N+1)/2 when TRANSR = !> 'C'. When TRANSR is 'N' the LDA is N+1 when N is even and N !> is odd. See the Note below for more details. !> !> On exit, the Hermitian inverse of the original matrix, in the !> same storage format. !>
INFO
!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument had an illegal value !> > 0: if INFO = i, the (i,i) element of the factor U or L is !> zero, and the inverse could not be computed. !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> We first consider Standard Packed Format when N is even. !> We give an example where N = 6. !> !> AP is Upper AP is Lower !> !> 00 01 02 03 04 05 00 !> 11 12 13 14 15 10 11 !> 22 23 24 25 20 21 22 !> 33 34 35 30 31 32 33 !> 44 45 40 41 42 43 44 !> 55 50 51 52 53 54 55 !> !> !> Let TRANSR = 'N'. RFP holds AP as follows: !> For UPLO = 'U' the upper trapezoid A(0:5,0:2) consists of the last !> three columns of AP upper. The lower triangle A(4:6,0:2) consists of !> conjugate-transpose of the first three columns of AP upper. !> For UPLO = 'L' the lower trapezoid A(1:6,0:2) consists of the first !> three columns of AP lower. The upper triangle A(0:2,0:2) consists of !> conjugate-transpose of the last three columns of AP lower. !> To denote conjugate we place -- above the element. This covers the !> case N even and TRANSR = 'N'. !> !> RFP A RFP A !> !> -- -- -- !> 03 04 05 33 43 53 !> -- -- !> 13 14 15 00 44 54 !> -- !> 23 24 25 10 11 55 !> !> 33 34 35 20 21 22 !> -- !> 00 44 45 30 31 32 !> -- -- !> 01 11 55 40 41 42 !> -- -- -- !> 02 12 22 50 51 52 !> !> Now let TRANSR = 'C'. RFP A in both UPLO cases is just the conjugate- !> transpose of RFP A above. One therefore gets: !> !> !> RFP A RFP A !> !> -- -- -- -- -- -- -- -- -- -- !> 03 13 23 33 00 01 02 33 00 10 20 30 40 50 !> -- -- -- -- -- -- -- -- -- -- !> 04 14 24 34 44 11 12 43 44 11 21 31 41 51 !> -- -- -- -- -- -- -- -- -- -- !> 05 15 25 35 45 55 22 53 54 55 22 32 42 52 !> !> !> We next consider Standard Packed Format when N is odd. !> We give an example where N = 5. !> !> AP is Upper AP is Lower !> !> 00 01 02 03 04 00 !> 11 12 13 14 10 11 !> 22 23 24 20 21 22 !> 33 34 30 31 32 33 !> 44 40 41 42 43 44 !> !> !> Let TRANSR = 'N'. RFP holds AP as follows: !> For UPLO = 'U' the upper trapezoid A(0:4,0:2) consists of the last !> three columns of AP upper. The lower triangle A(3:4,0:1) consists of !> conjugate-transpose of the first two columns of AP upper. !> For UPLO = 'L' the lower trapezoid A(0:4,0:2) consists of the first !> three columns of AP lower. The upper triangle A(0:1,1:2) consists of !> conjugate-transpose of the last two columns of AP lower. !> To denote conjugate we place -- above the element. This covers the !> case N odd and TRANSR = 'N'. !> !> RFP A RFP A !> !> -- -- !> 02 03 04 00 33 43 !> -- !> 12 13 14 10 11 44 !> !> 22 23 24 20 21 22 !> -- !> 00 33 34 30 31 32 !> -- -- !> 01 11 44 40 41 42 !> !> Now let TRANSR = 'C'. RFP A in both UPLO cases is just the conjugate- !> transpose of RFP A above. One therefore gets: !> !> !> RFP A RFP A !> !> -- -- -- -- -- -- -- -- -- !> 02 12 22 00 01 00 10 20 30 40 50 !> -- -- -- -- -- -- -- -- -- !> 03 13 23 33 11 33 11 21 31 41 51 !> -- -- -- -- -- -- -- -- -- !> 04 14 24 34 44 43 44 22 32 42 52 !>
Definition at line 211 of file zpftri.f.
Author¶
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