sget39.f - Man Page

TESTING/EIG/sget39.f

Synopsis

Functions/Subroutines

subroutine sget39 (rmax, lmax, ninfo, knt)
SGET39

Function/Subroutine Documentation

subroutine sget39 (real rmax, integer lmax, integer ninfo, integer knt)

SGET39

Purpose:

 SGET39 tests SLAQTR, 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 STRSNA.

 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 REAL
          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 sget39.f.

Author

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Referenced By

The man page sget39(3) is an alias of sget39.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK