dla_porcond-f(3)

dla_porcond.f –

Synopsis

Functions/Subroutines

DOUBLE PRECISION function dla_porcond (UPLO, N, A, LDA, AF, LDAF, CMODE, C, INFO, WORK, IWORK)
DLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix.

Function/Subroutine Documentation

DOUBLE PRECISION function dla_porcond (characterUPLO, integerN, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( ldaf, * )AF, integerLDAF, integerCMODE, double precision, dimension( * )C, integerINFO, double precision, dimension( * )WORK, integer, dimension( * )IWORK)

DLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix.

Purpose:

 DLA_PORCOND Estimates the Skeel condition number of op(A) * op2(C)
 where op2 is determined by CMODE as follows
 CMODE = 1 op2(C) = C
 CMODE = 0 op2(C) = I
 CMODE = -1 op2(C) = inv(C)
 The Skeel condition number cond(A) = norminf( |inv(A)||A| )
 is computed by computing scaling factors R such that
 diag(R)*A*op2(C) is row equilibrated and computing the standard
 infinity-norm condition number.

 

Parameters:

UPLO

 UPLO is CHARACTER*1
 = 'U': Upper triangle of A is stored;
 = 'L': Lower triangle of A is stored.

N

 N is INTEGER
 The number of linear equations, i.e., the order of the
 matrix A. N >= 0.

A

 A is DOUBLE PRECISION array, dimension (LDA,N)
 On entry, the N-by-N matrix A.

LDA

 LDA is INTEGER
 The leading dimension of the array A. LDA >= max(1,N).

AF

 AF is DOUBLE PRECISION array, dimension (LDAF,N)
 The triangular factor U or L from the Cholesky factorization
 A = U**T*U or A = L*L**T, as computed by DPOTRF.

LDAF

 LDAF is INTEGER
 The leading dimension of the array AF. LDAF >= max(1,N).

CMODE

 CMODE is INTEGER
 Determines op2(C) in the formula op(A) * op2(C) as follows:
 CMODE = 1 op2(C) = C
 CMODE = 0 op2(C) = I
 CMODE = -1 op2(C) = inv(C)

C

 C is DOUBLE PRECISION array, dimension (N)
 The vector C in the formula op(A) * op2(C).

INFO

 INFO is INTEGER
 = 0: Successful exit.
 i > 0: The ith argument is invalid.

WORK

 WORK is DOUBLE PRECISION array, dimension (3*N).
 Workspace.

IWORK

 IWORK is INTEGER array, dimension (N).
 Workspace.

 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 141 of file dla_porcond.f.

Author

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