cptcon.f

Section: LAPACK (3)
Updated: Tue Nov 14 2017
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NAME

cptcon.f  

SYNOPSIS


 

Functions/Subroutines


subroutine cptcon (N, D, E, ANORM, RCOND, RWORK, INFO)
CPTCON  

Function/Subroutine 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.

Date:

December 2016

Further Details:

  The method used is described in Nicholas J. Higham, "Efficient
  Algorithms for Computing the Condition Number of a Tridiagonal
  Matrix", SIAM J. Sci. Stat. Comput., Vol. 7, No. 1, January 1986.


 

Definition at line 121 of file cptcon.f.  

Author

Generated automatically by Doxygen for LAPACK from the source code.


 

Index

NAME
SYNOPSIS
Functions/Subroutines
Function/Subroutine Documentation
subroutine cptcon (integer N, real, dimension( * ) D, complex, dimension( * ) E, real ANORM, real RCOND, real, dimension( * ) RWORK, integer INFO)
Author
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