sla_lin_berr - wise relative backward error
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);
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)