SGTT02 computes the residual for the solution to a tridiagonal


 system of equations:


    RESID = norm(B - op(A)*X) / (norm(op(A)) * norm(X) * EPS),


 where EPS is the machine epsilon.


 The norm used is the 1-norm.

TRANS

          TRANS is CHARACTER


          Specifies the form of the residual.


          = 'N':  B - A    * X  (No transpose)


          = 'T':  B - A**T * X  (Transpose)


          = 'C':  B - A**H * X  (Conjugate transpose = Transpose)

N

          N is INTEGER


          The order of the matrix A.  N >= 0.

NRHS

          NRHS is INTEGER


          The number of right hand sides, i.e., the number of columns


          of the matrices B and X.  NRHS >= 0.

DL

          DL is REAL array, dimension (N-1)


          The (n-1) sub-diagonal elements of A.

D

          D is REAL array, dimension (N)


          The diagonal elements of A.

DU

          DU is REAL array, dimension (N-1)


          The (n-1) super-diagonal elements of A.

X

          X is REAL array, dimension (LDX,NRHS)


          The computed solution vectors X.

LDX

          LDX is INTEGER


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

B

          B is REAL array, dimension (LDB,NRHS)


          On entry, the right hand side vectors for the system of


          linear equations.


          On exit, B is overwritten with the difference B - op(A)*X.

LDB

          LDB is INTEGER


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

RESID

          RESID is REAL


          norm(B - op(A)*X) / (norm(op(A)) * norm(X) * EPS)

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