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| pptri(3) | LAPACK | pptri(3) |
NAME
pptri - pptri: triangular inverse
SYNOPSIS
Functions
subroutine cpptri (uplo, n, ap, info)
CPPTRI subroutine dpptri (uplo, n, ap, info)
DPPTRI subroutine spptri (uplo, n, ap, info)
SPPTRI subroutine zpptri (uplo, n, ap, info)
ZPPTRI
Detailed Description
Function Documentation
subroutine cpptri (character uplo, integer n, complex, dimension( * ) ap, integer info)
CPPTRI
Purpose:
CPPTRI 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 CPPTRF.
Parameters
UPLO is CHARACTER*1
= 'U': Upper triangular factor is stored in AP;
= 'L': Lower triangular factor is stored in AP.
N
N is INTEGER
The order of the matrix A. N >= 0.
AP
AP is COMPLEX array, dimension (N*(N+1)/2)
On entry, the triangular factor U or L from the Cholesky
factorization A = U**H*U or A = L*L**H, packed columnwise as
a linear array. The j-th column of U or L is stored in the
array AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
On exit, the upper or lower triangle of the (Hermitian)
inverse of A, overwriting the input factor U or L.
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 California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 92 of file cpptri.f.
subroutine dpptri (character uplo, integer n, double precision, dimension( * ) ap, integer info)
DPPTRI
Purpose:
DPPTRI computes the inverse of a real symmetric positive definite
matrix A using the Cholesky factorization A = U**T*U or A = L*L**T
computed by DPPTRF.
Parameters
UPLO is CHARACTER*1
= 'U': Upper triangular factor is stored in AP;
= 'L': Lower triangular factor is stored in AP.
N
N is INTEGER
The order of the matrix A. N >= 0.
AP
AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
On entry, the triangular factor U or L from the Cholesky
factorization A = U**T*U or A = L*L**T, packed columnwise as
a linear array. The j-th column of U or L is stored in the
array AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
On exit, the upper or lower triangle of the (symmetric)
inverse of A, overwriting the input factor U or L.
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 California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 92 of file dpptri.f.
subroutine spptri (character uplo, integer n, real, dimension( * ) ap, integer info)
SPPTRI
Purpose:
SPPTRI computes the inverse of a real symmetric positive definite
matrix A using the Cholesky factorization A = U**T*U or A = L*L**T
computed by SPPTRF.
Parameters
UPLO is CHARACTER*1
= 'U': Upper triangular factor is stored in AP;
= 'L': Lower triangular factor is stored in AP.
N
N is INTEGER
The order of the matrix A. N >= 0.
AP
AP is REAL array, dimension (N*(N+1)/2)
On entry, the triangular factor U or L from the Cholesky
factorization A = U**T*U or A = L*L**T, packed columnwise as
a linear array. The j-th column of U or L is stored in the
array AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
On exit, the upper or lower triangle of the (symmetric)
inverse of A, overwriting the input factor U or L.
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 California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 92 of file spptri.f.
subroutine zpptri (character uplo, integer n, complex*16, dimension( * ) ap, integer info)
ZPPTRI
Purpose:
ZPPTRI 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 ZPPTRF.
Parameters
UPLO is CHARACTER*1
= 'U': Upper triangular factor is stored in AP;
= 'L': Lower triangular factor is stored in AP.
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 triangular factor U or L from the Cholesky
factorization A = U**H*U or A = L*L**H, packed columnwise as
a linear array. The j-th column of U or L is stored in the
array AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
On exit, the upper or lower triangle of the (Hermitian)
inverse of A, overwriting the input factor U or L.
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 California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 92 of file zpptri.f.
Author
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