LAPACK 3.11.0
LAPACK: Linear Algebra PACKage

◆ dget04()

subroutine dget04 ( integer  N,
integer  NRHS,
double precision, dimension( ldx, * )  X,
integer  LDX,
double precision, dimension( ldxact, * )  XACT,
integer  LDXACT,
double precision  RCOND,
double precision  RESID 
)

DGET04

Purpose:
 DGET04 computes the difference between a computed solution and the
 true solution to a system of linear equations.

 RESID =  ( norm(X-XACT) * RCOND ) / ( norm(XACT) * EPS ),
 where RCOND is the reciprocal of the condition number and EPS is the
 machine epsilon.
Parameters
[in]N
          N is INTEGER
          The number of rows of the matrices X and XACT.  N >= 0.
[in]NRHS
          NRHS is INTEGER
          The number of columns of the matrices X and XACT.  NRHS >= 0.
[in]X
          X is DOUBLE PRECISION array, dimension (LDX,NRHS)
          The computed solution vectors.  Each vector is stored as a
          column of the matrix X.
[in]LDX
          LDX is INTEGER
          The leading dimension of the array X.  LDX >= max(1,N).
[in]XACT
          XACT is DOUBLE PRECISION array, dimension( LDX, NRHS )
          The exact solution vectors.  Each vector is stored as a
          column of the matrix XACT.
[in]LDXACT
          LDXACT is INTEGER
          The leading dimension of the array XACT.  LDXACT >= max(1,N).
[in]RCOND
          RCOND is DOUBLE PRECISION
          The reciprocal of the condition number of the coefficient
          matrix in the system of equations.
[out]RESID
          RESID is DOUBLE PRECISION
          The maximum over the NRHS solution vectors of
          ( norm(X-XACT) * RCOND ) / ( norm(XACT) * EPS )
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.