dla_lin_berr (3p)

Name

dla_lin_berr - wise relative backward error

Synopsis

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


INTEGER N, NZ, NRHS

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

DOUBLE PRECISION RES(N,NRHS)


SUBROUTINE DLA_LIN_BERR_64 (N, NZ, NRHS, RES, AYB, BERR)


INTEGER*8 N, NZ, NRHS

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

DOUBLE PRECISION RES(N,NRHS)


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


INTEGER :: N, NZ, NRHS

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

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


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


INTEGER(8) :: N, NZ, NRHS

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

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


C INTERFACE
#include <sunperf.h>

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


void dla_lin_berr_64 (long n, long nz, long nrhs, double  *res,  double
*ayb, double *berr);

Description

Oracle Solaris Studio Performance Library                     dla_lin_berr(3P)



NAME
       dla_lin_berr - compute a component-wise relative backward error


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


       INTEGER N, NZ, NRHS

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

       DOUBLE PRECISION RES(N,NRHS)


       SUBROUTINE DLA_LIN_BERR_64 (N, NZ, NRHS, RES, AYB, BERR)


       INTEGER*8 N, NZ, NRHS

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

       DOUBLE PRECISION RES(N,NRHS)


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


       INTEGER :: N, NZ, NRHS

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

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


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


       INTEGER(8) :: N, NZ, NRHS

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

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


   C INTERFACE
       #include <sunperf.h>

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


       void dla_lin_berr_64 (long n, long nz, long nrhs, double  *res,  double
                 *ayb, double *berr);


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 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 resid-
                 ual matrix, i.e., the matrix R in the relative backward 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
                 dla_gerfsx_extended.f).


       BERR (output)
                 BERR is DOUBLE PRECISION array, dimension (NRHS)
                 The component-wise relative backward error from  the  formula
                 above.




                                  7 Nov 2015                  dla_lin_berr(3P)