dget39.f - Man Page

subroutine dget39 (rmax, lmax, ninfo, knt)
DGET39

DGET39

Purpose:

 DGET39 tests DLAQTR, a routine for solving the real or
 special complex quasi upper triangular system

      op(T)*p = scale*c,
 or
      op(T + iB)*(p+iq) = scale*(c+id),

 in real arithmetic. T is upper quasi-triangular.
 If it is complex, then the first diagonal block of T must be
 1 by 1, B has the special structure

                B = [ b(1) b(2) ... b(n) ]
                    [       w            ]
                    [           w        ]
                    [              .     ]
                    [                 w  ]

 op(A) = A or A', where A' denotes the conjugate transpose of
 the matrix A.

 On input, X = [ c ].  On output, X = [ p ].
               [ d ]                  [ q ]

 Scale is an output less than or equal to 1, chosen to avoid
 overflow in X.
 This subroutine is specially designed for the condition number
 estimation in the eigenproblem routine DTRSNA.

 The test code verifies that the following residual is order 1:

      ||(T+i*B)*(x1+i*x2) - scale*(d1+i*d2)||
    -----------------------------------------
        max(ulp*(||T||+||B||)*(||x1||+||x2||),
            (||T||+||B||)*smlnum/ulp,
            smlnum)

 (The (||T||+||B||)*smlnum/ulp term accounts for possible
  (gradual or nongradual) underflow in x1 and x2.)

Parameters

RMAX

          RMAX is DOUBLE PRECISION
          Value of the largest test ratio.

LMAX

          LMAX is INTEGER
          Example number where largest test ratio achieved.

NINFO

          NINFO is INTEGER
          Number of examples where INFO is nonzero.

KNT

          KNT is INTEGER
          Total number of examples tested.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 102 of file dget39.f.