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dla_gercond-f(3)

dla_gercond.f –

Synopsis

Functions/Subroutines

DOUBLE PRECISION function dla_gercond (TRANS, N, A, LDA, AF, LDAF, IPIV, CMODE, C, INFO, WORK, IWORK)
DLA_GERCOND estimates the Skeel condition number for a general matrix.

Function/Subroutine Documentation

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

DLA_GERCOND estimates the Skeel condition number for a general matrix.

Purpose:

 DLA_GERCOND 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:

TRANS

 TRANS is CHARACTER*1
 Specifies the form of the system of equations:
 = 'N': A * X = B (No transpose)
 = 'T': A**T * X = B (Transpose)
 = 'C': A**H * X = B (Conjugate Transpose = Transpose)

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 factors L and U from the factorization
 A = P*L*U as computed by DGETRF.

LDAF

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

IPIV

 IPIV is INTEGER array, dimension (N)
 The pivot indices from the factorization A = P*L*U
 as computed by DGETRF; row i of the matrix was interchanged
 with row IPIV(i).

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 151 of file dla_gercond.f.

Author

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