
sptcon.f(3) LAPACK sptcon.f(3)
NAME
sptcon.f 
SYNOPSIS
Functions/Subroutines
subroutine sptcon (N, D, E, ANORM, RCOND, WORK, INFO)
SPTCON
Function/Subroutine Documentation
subroutine sptcon (integerN, real, dimension( * )D, real, dimension( * )E, realANORM,
realRCOND, real, dimension( * )WORK, integerINFO)
SPTCON
Purpose:
SPTCON computes the reciprocal of the condition number (in the
1norm) 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 (N1)
The (n1) offdiagonal elements of the unit bidiagonal factor
U or L from the factorization of A, as computed by SPTTRF.
ANORM
ANORM is REAL
The 1norm 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
1norm 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 ith argument had an illegal value
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
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 119 of file sptcon.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 sptcon.f(3) 
