sla_lin_berr.f man page

sla_lin_berr.f —

Synopsis

Functions/Subroutines

subroutine sla_lin_berr (N, NZ, NRHS, RES, AYB, BERR)
SLA_LIN_BERR computes a component-wise relative backward error.

Function/Subroutine Documentation

subroutine sla_lin_berr (integerN, integerNZ, integerNRHS, real, dimension( n, nrhs )RES, real, dimension( n, nrhs )AYB, real, dimension( nrhs )BERR)

SLA_LIN_BERR computes a component-wise relative backward error.

Purpose:

SLA_LIN_BERR computes componentwise relative backward error from
the formula
    max(i) ( abs(R(i)) / ( abs(op(A_s))*abs(Y) + abs(B_s) )(i) )
where abs(Z) is the componentwise absolute value of the matrix
or vector Z.

Parameters:

N

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

NZ

     NZ is INTEGER
We add (NZ+1)*SLAMCH( 'Safe minimum' ) to R(i) in the numerator to
guard against spuriously zero residuals. Default value is N.

NRHS

     NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrices AYB, RES, and BERR.  NRHS >= 0.

RES

     RES is REAL array, dimension (N,NRHS)
The residual matrix, i.e., the matrix R in the relative backward
error formula above.

AYB

     AYB is REAL array, dimension (N, NRHS)
The denominator in the relative backward error formula above, i.e.,
the matrix abs(op(A_s))*abs(Y) + abs(B_s). The matrices A, Y, and B
are from iterative refinement (see sla_gerfsx_extended.f).

BERR

     BERR is REAL array, dimension (NRHS)
The componentwise relative backward error from the formula above.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 102 of file sla_lin_berr.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

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

Sat Nov 16 2013 Version 3.4.2 LAPACK