!>
!> DPTT02 computes the residual for the solution to a symmetric
!> tridiagonal system of equations:
!>    RESID = norm(B - A*X) / (norm(A) * norm(X) * EPS),
!> where EPS is the machine epsilon.
!> 

N

!>          N is INTEGER
!>          The order of the matrix A.
!> 

NRHS

!>          NRHS is INTEGER
!>          The number of right hand sides, i.e., the number of columns
!>          of the matrices B and X.  NRHS >= 0.
!> 

D

!>          D is DOUBLE PRECISION array, dimension (N)
!>          The n diagonal elements of the tridiagonal matrix A.
!> 

E

!>          E is DOUBLE PRECISION array, dimension (N-1)
!>          The (n-1) subdiagonal elements of the tridiagonal matrix A.
!> 

X

!>          X is DOUBLE PRECISION array, dimension (LDX,NRHS)
!>          The n by nrhs matrix of solution vectors X.
!> 

LDX

!>          LDX is INTEGER
!>          The leading dimension of the array X.  LDX >= max(1,N).
!> 

B

!>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
!>          On entry, the n by nrhs matrix of right hand side vectors B.
!>          On exit, B is overwritten with the difference B - A*X.
!> 

LDB

!>          LDB is INTEGER
!>          The leading dimension of the array B.  LDB >= max(1,N).
!> 

RESID

!>          RESID is DOUBLE PRECISION
!>          norm(B - A*X) / (norm(A) * norm(X) * EPS)
!> 

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