ptcon(3)

NAME
ptcon - ptcon: condition number estimate

SYNOPSIS

  Functions

subroutine cptcon (n, d, e, anorm, rcond, rwork, info)
CPTCON
subroutine dptcon (n, d, e, anorm, rcond, work, info)
DPTCON
subroutine sptcon (n, d, e, anorm, rcond, work, info)
SPTCON
subroutine zptcon (n, d, e, anorm, rcond, rwork, info)
ZPTCON

Detailed Description

Function Documentation

  subroutine cptcon (integer n, real, dimension( * ) d, complex, dimension( * ) e, real anorm, real rcond, real, dimension( * ) rwork, integer info)

CPTCON

Purpose:

    !>
    !> CPTCON computes the reciprocal of the condition number (in the
    !> 1-norm) of a complex Hermitian positive definite tridiagonal matrix
    !> using the factorization A = L*D*L**H or A = U**H*D*U computed by
    !> CPTTRF.
    !>
    !> Norm(inv(A)) is computed by a direct method, and the reciprocal of
    !> the condition number is computed as
    !>                  RCOND = 1 / (ANORM * norm(inv(A))).
    !>

Parameters
    N

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

    D

    !>          D is REAL array, dimension (N)
    !>          The n diagonal elements of the diagonal matrix D from the
    !>          factorization of A, as computed by CPTTRF.
    !>

    E

    !>          E is COMPLEX array, dimension (N-1)
    !>          The (n-1) off-diagonal elements of the unit bidiagonal factor
    !>          U or L from the factorization of A, as computed by CPTTRF.
    !>

    ANORM

    !>          ANORM is REAL
    !>          The 1-norm of the original matrix A.
    !>

    RCOND

    !>          RCOND is REAL
    !>          The reciprocal of the condition number of the matrix A,
    !>          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is the
    !>          1-norm of inv(A) computed in this routine.
    !>

    RWORK

    !>          RWORK is REAL array, dimension (N)
    !>

    INFO

    !>          INFO is INTEGER
    !>          = 0:  successful exit
    !>          < 0:  if INFO = -i, the i-th argument had an illegal value
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Further Details:

    !>
    !>  The method used is described in Nicholas J. Higham, , SIAM J. Sci. Stat. Comput., Vol. 7, No. 1, January 1986.
    !>

  subroutine dptcon (integer n, double precision, dimension( * ) d, double precision, dimension( * ) e, double precision anorm, double precision rcond, double precision, dimension( * ) work, integer info)

DPTCON

Purpose:

    !>
    !> DPTCON computes the reciprocal of the condition number (in the
    !> 1-norm) of a real symmetric positive definite tridiagonal matrix
    !> using the factorization A = L*D*L**T or A = U**T*D*U computed by
    !> DPTTRF.
    !>
    !> Norm(inv(A)) is computed by a direct method, and the reciprocal of
    !> the condition number is computed as
    !>              RCOND = 1 / (ANORM * norm(inv(A))).
    !>

Parameters
    N

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

    D

    !>          D is DOUBLE PRECISION array, dimension (N)
    !>          The n diagonal elements of the diagonal matrix D from the
    !>          factorization of A, as computed by DPTTRF.
    !>

    E

    !>          E is DOUBLE PRECISION array, dimension (N-1)
    !>          The (n-1) off-diagonal elements of the unit bidiagonal factor
    !>          U or L from the factorization of A,  as computed by DPTTRF.
    !>

    ANORM

    !>          ANORM is DOUBLE PRECISION
    !>          The 1-norm of the original matrix A.
    !>

    RCOND

    !>          RCOND is DOUBLE PRECISION
    !>          The reciprocal of the condition number of the matrix A,
    !>          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is the
    !>          1-norm of inv(A) computed in this routine.
    !>

    WORK

    !>          WORK is DOUBLE PRECISION array, dimension (N)
    !>

    INFO

    !>          INFO is INTEGER
    !>          = 0:  successful exit
    !>          < 0:  if INFO = -i, the i-th argument had an illegal value
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Further Details:

    !>
    !>  The method used is described in Nicholas J. Higham, , SIAM J. Sci. Stat. Comput., Vol. 7, No. 1, January 1986.
    !>

  subroutine sptcon (integer n, real, dimension( * ) d, real, dimension( * ) e, real anorm, real rcond, real, dimension( * ) work, integer info)

SPTCON

Purpose:

    !>
    !> SPTCON computes the reciprocal of the condition number (in the
    !> 1-norm) of a real symmetric positive definite tridiagonal matrix
    !> using the factorization A = L*D*L**T or A = U**T*D*U computed by
    !> SPTTRF.
    !>
    !> Norm(inv(A)) is computed by a direct method, and the reciprocal of
    !> the condition number is computed as
    !>              RCOND = 1 / (ANORM * norm(inv(A))).
    !>

Parameters
    N

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

    D

    !>          D is REAL array, dimension (N)
    !>          The n diagonal elements of the diagonal matrix D from the
    !>          factorization of A, as computed by SPTTRF.
    !>

    E

    !>          E is REAL array, dimension (N-1)
    !>          The (n-1) off-diagonal elements of the unit bidiagonal factor
    !>          U or L from the factorization of A,  as computed by SPTTRF.
    !>

    ANORM

    !>          ANORM is REAL
    !>          The 1-norm of the original matrix A.
    !>

    RCOND

    !>          RCOND is REAL
    !>          The reciprocal of the condition number of the matrix A,
    !>          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is the
    !>          1-norm of inv(A) computed in this routine.
    !>

    WORK

    !>          WORK is REAL array, dimension (N)
    !>

    INFO

    !>          INFO is INTEGER
    !>          = 0:  successful exit
    !>          < 0:  if INFO = -i, the i-th argument had an illegal value
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Further Details:

    !>
    !>  The method used is described in Nicholas J. Higham, , SIAM J. Sci. Stat. Comput., Vol. 7, No. 1, January 1986.
    !>

  subroutine zptcon (integer n, double precision, dimension( * ) d, complex*16, dimension( * ) e, double precision anorm, double precision rcond, double precision, dimension( * ) rwork, integer info)

ZPTCON

Purpose:

    !>
    !> ZPTCON computes the reciprocal of the condition number (in the
    !> 1-norm) of a complex Hermitian positive definite tridiagonal matrix
    !> using the factorization A = L*D*L**H or A = U**H*D*U computed by
    !> ZPTTRF.
    !>
    !> Norm(inv(A)) is computed by a direct method, and the reciprocal of
    !> the condition number is computed as
    !>                  RCOND = 1 / (ANORM * norm(inv(A))).
    !>

Parameters
    N

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

    D

    !>          D is DOUBLE PRECISION array, dimension (N)
    !>          The n diagonal elements of the diagonal matrix D from the
    !>          factorization of A, as computed by ZPTTRF.
    !>

    E

    !>          E is COMPLEX*16 array, dimension (N-1)
    !>          The (n-1) off-diagonal elements of the unit bidiagonal factor
    !>          U or L from the factorization of A, as computed by ZPTTRF.
    !>

    ANORM

    !>          ANORM is DOUBLE PRECISION
    !>          The 1-norm of the original matrix A.
    !>

    RCOND

    !>          RCOND is DOUBLE PRECISION
    !>          The reciprocal of the condition number of the matrix A,
    !>          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is the
    !>          1-norm of inv(A) computed in this routine.
    !>

    RWORK

    !>          RWORK is DOUBLE PRECISION array, dimension (N)
    !>

    INFO

    !>          INFO is INTEGER
    !>          = 0:  successful exit
    !>          < 0:  if INFO = -i, the i-th argument had an illegal value
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Further Details:

    !>
    !>  The method used is described in Nicholas J. Higham, , SIAM J. Sci. Stat. Comput., Vol. 7, No. 1, January 1986.
    !>

Author

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