SRC/dla_lin_berr.f(3)      Library Functions Manual      SRC/dla_lin_berr.f(3)

NAME
       SRC/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 (integer n, integer nz, integer nrhs, 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.

       Definition at line 100 of file dla_lin_berr.f.

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

LAPACK                          Version 3.12.0           SRC/dla_lin_berr.f(3)