sla_gercond.f man page

sla_gercond.f —

Synopsis

Functions/Subroutines

REAL function sla_gercond (TRANS, N, A, LDA, AF, LDAF, IPIV, CMODE, C, INFO, WORK, IWORK)
SLA_GERCOND estimates the Skeel condition number for a general matrix.

Function/Subroutine Documentation

REAL function sla_gercond (characterTRANS, integerN, real, dimension( lda, * )A, integerLDA, real, dimension( ldaf, * )AF, integerLDAF, integer, dimension( * )IPIV, integerCMODE, real, dimension( * )C, integerINFO, real, dimension( * )WORK, integer, dimension( * )IWORK)

SLA_GERCOND estimates the Skeel condition number for a general matrix.

Purpose:

SLA_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 REAL 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 REAL array, dimension (LDAF,N)
The factors L and U from the factorization
A = P*L*U as computed by SGETRF.

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 SGETRF; 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 REAL 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 REAL array, dimension (3*N).
Workspace.

IWORK

     IWORK is INTEGER array, dimension (N).
Workspace.2

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 150 of file sla_gercond.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

sla_gercond(3) is an alias of sla_gercond.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK