zla_lin_berr (3p)

Name

zla_lin_berr - wise relative backward error

Synopsis

SUBROUTINE ZLA_LIN_BERR (N, NZ, NRHS, RES, AYB, BERR)


INTEGER N, NZ, NRHS

DOUBLE PRECISION AYB(N,NRHS), BERR(NRHS)

DOUBLE COMPLEX RES(N,NRHS)


SUBROUTINE ZLA_LIN_BERR_64 (N, NZ, NRHS, RES, AYB, BERR)


INTEGER*8 N, NZ, NRHS

DOUBLE PRECISION AYB(N,NRHS), BERR(NRHS)

DOUBLE COMPLEX RES(N,NRHS)


F95 INTERFACE
SUBROUTINE LA_LIN_BERR (N, NZ, NRHS, RES, AYB, BERR)


INTEGER :: N, NZ, NRHS

REAL(8), DIMENSION(:,:) :: AYB

REAL(8), DIMENSION(:) :: BERR

COMPLEX(8), DIMENSION(:,:) :: RES


SUBROUTINE LA_LIN_BERR_64 (N, NZ, NRHS, RES, AYB, BERR)


INTEGER(8) :: N, NZ, NRHS

REAL(8), DIMENSION(:,:) :: AYB

REAL(8), DIMENSION(:) :: BERR

COMPLEX(8), DIMENSION(:,:) :: RES


C INTERFACE
#include <sunperf.h>

void  zla_lin_berr (int n, int nz, int nrhs, doublecomplex *res, double
*ayb, double *berr);


void zla_lin_berr_64 (long n, long nz, long nrhs,  doublecomplex  *res,
double *ayb, double *berr);

Description

Oracle Solaris Studio Performance Library                     zla_lin_berr(3P)



NAME
       zla_lin_berr - compute a component-wise relative backward error


SYNOPSIS
       SUBROUTINE ZLA_LIN_BERR (N, NZ, NRHS, RES, AYB, BERR)


       INTEGER N, NZ, NRHS

       DOUBLE PRECISION AYB(N,NRHS), BERR(NRHS)

       DOUBLE COMPLEX RES(N,NRHS)


       SUBROUTINE ZLA_LIN_BERR_64 (N, NZ, NRHS, RES, AYB, BERR)


       INTEGER*8 N, NZ, NRHS

       DOUBLE PRECISION AYB(N,NRHS), BERR(NRHS)

       DOUBLE COMPLEX RES(N,NRHS)


   F95 INTERFACE
       SUBROUTINE LA_LIN_BERR (N, NZ, NRHS, RES, AYB, BERR)


       INTEGER :: N, NZ, NRHS

       REAL(8), DIMENSION(:,:) :: AYB

       REAL(8), DIMENSION(:) :: BERR

       COMPLEX(8), DIMENSION(:,:) :: RES


       SUBROUTINE LA_LIN_BERR_64 (N, NZ, NRHS, RES, AYB, BERR)


       INTEGER(8) :: N, NZ, NRHS

       REAL(8), DIMENSION(:,:) :: AYB

       REAL(8), DIMENSION(:) :: BERR

       COMPLEX(8), DIMENSION(:,:) :: RES


   C INTERFACE
       #include <sunperf.h>

       void  zla_lin_berr (int n, int nz, int nrhs, doublecomplex *res, double
                 *ayb, double *berr);


       void zla_lin_berr_64 (long n, long nz, long nrhs,  doublecomplex  *res,
                 double *ayb, double *berr);


PURPOSE
       zla_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 vec-
       tor Z.


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


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


       NRHS (input)
                 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 (input)
                 RES is DOUBLE PRECISION array, dimension (N,NRHS)
                 The residual matrix, i.e., the matrix R in the relative back-
                 ward error formula above.


       AYB (input)
                 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
                 zla_gerfsx_extended.f).


       BERR (output)
                 BERR is COMPLEX*16 array, dimension (NRHS)
                 The componentwise relative backward error  from  the  formula
                 above.




                                  7 Nov 2015                  zla_lin_berr(3P)