# CentOS 7.0 - man page for dla_lin_berr (centos section 3)

```dla_lin_berr.f(3)						      LAPACK							 dla_lin_berr.f(3)

NAME
dla_lin_berr.f -

SYNOPSIS
Functions/Subroutines
subroutine dla_lin_berr (N, NZ, NRHS, RES, AYB, BERR)
DLA_LIN_BERR computes a component-wise relative backward error.

Function/Subroutine Documentation
subroutine dla_lin_berr (integerN, integerNZ, integerNRHS, double precision, dimension( n, nrhs )RES, double precision, dimension( n, nrhs
)AYB, double precision, dimension( nrhs )BERR)
DLA_LIN_BERR computes a component-wise relative backward error.

Purpose:

DLA_LIN_BERR computes component-wise 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 component-wise 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 DOUBLE PRECISION array, dimension (N,NRHS)
The residual matrix, i.e., the matrix R in the relative backward
error formula above.

AYB

AYB is DOUBLE PRECISION 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 dla_gerfsx_extended.f).

BERR

BERR is DOUBLE PRECISION array, dimension (NRHS)
The component-wise 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 dla_lin_berr.f.

Author
Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						 dla_lin_berr.f(3)```