# dget39.f - Man Page

TESTING/EIG/dget39.f

## Synopsis

### Functions/Subroutines

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

## Function/Subroutine Documentation

### subroutine dget39 (double precision rmax, integer lmax, integer ninfo, integer knt)

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.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dget39(3) is an alias of dget39.f(3).

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