sla_lin_berr (3p)

Name

sla_lin_berr - wise relative backward error

Synopsis

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


INTEGER N, NZ, NRHS

REAL AYB(N,NRHS), BERR(NRHS)

REAL RES(N,NRHS)


SUBROUTINE SLA_LIN_BERR_64 (N, NZ, NRHS, RES, AYB, BERR)


INTEGER*8 N, NZ, NRHS

REAL AYB(N,NRHS), BERR(NRHS)

REAL RES(N,NRHS)


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


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

INTEGER :: N, NZ, NRHS

REAL, DIMENSION(:) :: BERR


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


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

INTEGER(8) :: N, NZ, NRHS

REAL, DIMENSION(:) :: BERR


C INTERFACE
#include <sunperf.h>

void  sla_lin_berr  (int  n,  int nz, int nrhs, float *res, float *ayb,
float *berr);


void sla_lin_berr_64 (long n, long nz, long  nrhs,  float  *res,  float
*ayb, float *berr);

Description

Oracle Solaris Studio Performance Library                     sla_lin_berr(3P)



NAME
       sla_lin_berr - compute a component-wise relative backward error


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


       INTEGER N, NZ, NRHS

       REAL AYB(N,NRHS), BERR(NRHS)

       REAL RES(N,NRHS)


       SUBROUTINE SLA_LIN_BERR_64 (N, NZ, NRHS, RES, AYB, BERR)


       INTEGER*8 N, NZ, NRHS

       REAL AYB(N,NRHS), BERR(NRHS)

       REAL RES(N,NRHS)


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


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

       INTEGER :: N, NZ, NRHS

       REAL, DIMENSION(:) :: BERR


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


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

       INTEGER(8) :: N, NZ, NRHS

       REAL, DIMENSION(:) :: BERR


   C INTERFACE
       #include <sunperf.h>

       void  sla_lin_berr  (int  n,  int nz, int nrhs, float *res, float *ayb,
                 float *berr);


       void sla_lin_berr_64 (long n, long nz, long  nrhs,  float  *res,  float
                 *ayb, float *berr);


PURPOSE
       sla_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 REAL array, dimension (N,NRHS)
                 The residual matrix, i.e., the matrix R in the relative back-
                 ward error formula above.


       AYB (input)
                 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
                 sla_gerfsx_extended.f).


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




                                  7 Nov 2015                  sla_lin_berr(3P)