cla_lin_berr.f man page

cla_lin_berr.f

Synopsis

Functions/Subroutines

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

Function/Subroutine Documentation

subroutine cla_lin_berr (integer N, integer NZ, integer NRHS, complex, dimension( n, nrhs ) RES, real, dimension( n, nrhs ) AYB, real, dimension( nrhs ) BERR)

CLA_LIN_BERR computes a component-wise relative backward error.

Purpose:

```    CLA_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 COMPLEX 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 cla_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

NAG Ltd.

Date:

June 2016

Definition at line 103 of file cla_lin_berr.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

The man page cla_lin_berr(3) is an alias of cla_lin_berr.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK