dla_syrcond.f

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

dla_syrcond.f  

SYNOPSIS


 

Functions/Subroutines


double precision function dla_syrcond (UPLO, N, A, LDA, AF, LDAF, IPIV, CMODE, C, INFO, WORK, IWORK)
DLA_SYRCOND estimates the Skeel condition number for a symmetric indefinite matrix.  

Function/Subroutine Documentation

 

double precision function dla_syrcond (character UPLO, integer N, double precision, dimension( lda, * ) A, integer LDA, double precision, dimension( ldaf, * ) AF, integer LDAF, integer, dimension( * ) IPIV, integer CMODE, double precision, dimension( * ) C, integer INFO, double precision, dimension( * ) WORK, integer, dimension( * ) IWORK)

DLA_SYRCOND estimates the Skeel condition number for a symmetric indefinite matrix.

Purpose:

    DLA_SYRCOND 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 block diagonal matrix D and the multipliers used to
     obtain the factor U or L as computed by DSYTRF.


LDAF

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


IPIV

          IPIV is INTEGER array, dimension (N)
     Details of the interchanges and the block structure of D
     as determined by DSYTRF.


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:

December 2016

Definition at line 150 of file dla_syrcond.f.  

Author

Generated automatically by Doxygen for LAPACK from the source code.


 

Index

NAME
SYNOPSIS
Functions/Subroutines
Function/Subroutine Documentation
double precision function dla_syrcond (character UPLO, integer N, double precision, dimension( lda, * ) A, integer LDA, double precision, dimension( ldaf, * ) AF, integer LDAF, integer, dimension( * ) IPIV, integer CMODE, double precision, dimension( * ) C, integer INFO, double precision, dimension( * ) WORK, integer, dimension( * ) IWORK)
Author
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