Man page - pttrf(3)

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Manual

pttrf

NAME
SYNOPSIS
Functions
Detailed Description
Function Documentation
subroutine cpttrf (integer n, real, dimension( * ) d, complex, dimension( *) e, integer info)
subroutine dpttrf (integer n, double precision, dimension( * ) d, doubleprecision, dimension( * ) e, integer info)
subroutine spttrf (integer n, real, dimension( * ) d, real, dimension( * )e, integer info)
subroutine zpttrf (integer n, double precision, dimension( * ) d,complex*16, dimension( * ) e, integer info)
Author

NAME

pttrf - pttrf: triangular factor

SYNOPSIS

Functions

subroutine cpttrf (n, d, e, info)
CPTTRF
subroutine dpttrf (n, d, e, info)
DPTTRF
subroutine spttrf (n, d, e, info)
SPTTRF
subroutine zpttrf (n, d, e, info)
ZPTTRF

Detailed Description

Function Documentation

subroutine cpttrf (integer n, real, dimension( * ) d, complex, dimension( *) e, integer info)

CPTTRF

Purpose:

CPTTRF computes the L*D*L**H factorization of a complex Hermitian
positive definite tridiagonal matrix A. The factorization may also
be regarded as having the form A = U**H *D*U.

Parameters

N

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

D

D is REAL array, dimension (N)
On entry, the n diagonal elements of the tridiagonal matrix
A. On exit, the n diagonal elements of the diagonal matrix
D from the L*D*L**H factorization of A.

E

E is COMPLEX array, dimension (N-1)
On entry, the (n-1) subdiagonal elements of the tridiagonal
matrix A. On exit, the (n-1) subdiagonal elements of the
unit bidiagonal factor L from the L*D*L**H factorization of A.
E can also be regarded as the superdiagonal of the unit
bidiagonal factor U from the U**H *D*U factorization of A.

INFO

INFO is INTEGER
= 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value
> 0: if INFO = k, the leading principal minor of order k
is not positive; if k < N, the factorization could not
be completed, while if k = N, the factorization was
completed, but D(N) <= 0.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

subroutine dpttrf (integer n, double precision, dimension( * ) d, doubleprecision, dimension( * ) e, integer info)

DPTTRF

Purpose:

DPTTRF computes the L*D*L**T factorization of a real symmetric
positive definite tridiagonal matrix A. The factorization may also
be regarded as having the form A = U**T*D*U.

Parameters

N

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

D

D is DOUBLE PRECISION array, dimension (N)
On entry, the n diagonal elements of the tridiagonal matrix
A. On exit, the n diagonal elements of the diagonal matrix
D from the L*D*L**T factorization of A.

E

E is DOUBLE PRECISION array, dimension (N-1)
On entry, the (n-1) subdiagonal elements of the tridiagonal
matrix A. On exit, the (n-1) subdiagonal elements of the
unit bidiagonal factor L from the L*D*L**T factorization of A.
E can also be regarded as the superdiagonal of the unit
bidiagonal factor U from the U**T*D*U factorization of A.

INFO

INFO is INTEGER
= 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value
> 0: if INFO = k, the leading principal minor of order k
is not positive; if k < N, the factorization could not
be completed, while if k = N, the factorization was
completed, but D(N) <= 0.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

subroutine spttrf (integer n, real, dimension( * ) d, real, dimension( * )e, integer info)

SPTTRF

Purpose:

SPTTRF computes the L*D*L**T factorization of a real symmetric
positive definite tridiagonal matrix A. The factorization may also
be regarded as having the form A = U**T*D*U.

Parameters

N

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

D

D is REAL array, dimension (N)
On entry, the n diagonal elements of the tridiagonal matrix
A. On exit, the n diagonal elements of the diagonal matrix
D from the L*D*L**T factorization of A.

E

E is REAL array, dimension (N-1)
On entry, the (n-1) subdiagonal elements of the tridiagonal
matrix A. On exit, the (n-1) subdiagonal elements of the
unit bidiagonal factor L from the L*D*L**T factorization of A.
E can also be regarded as the superdiagonal of the unit
bidiagonal factor U from the U**T*D*U factorization of A.

INFO

INFO is INTEGER
= 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value
> 0: if INFO = k, the leading principal minor of order k
is not positive; if k < N, the factorization could not
be completed, while if k = N, the factorization was
completed, but D(N) <= 0.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

subroutine zpttrf (integer n, double precision, dimension( * ) d,complex*16, dimension( * ) e, integer info)

ZPTTRF

Purpose:

ZPTTRF computes the L*D*L**H factorization of a complex Hermitian
positive definite tridiagonal matrix A. The factorization may also
be regarded as having the form A = U**H *D*U.

Parameters

N

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

D

D is DOUBLE PRECISION array, dimension (N)
On entry, the n diagonal elements of the tridiagonal matrix
A. On exit, the n diagonal elements of the diagonal matrix
D from the L*D*L**H factorization of A.

E

E is COMPLEX*16 array, dimension (N-1)
On entry, the (n-1) subdiagonal elements of the tridiagonal
matrix A. On exit, the (n-1) subdiagonal elements of the
unit bidiagonal factor L from the L*D*L**H factorization of A.
E can also be regarded as the superdiagonal of the unit
bidiagonal factor U from the U**H *D*U factorization of A.

INFO

INFO is INTEGER
= 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value
> 0: if INFO = k, the leading principal minor of order k
is not positive; if k < N, the factorization could not
be completed, while if k = N, the factorization was
completed, but D(N) <= 0.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Author

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