NAG CL Interface
f11bfc (real_​gen_​basic_​diag)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{itn}$ – Integer * Output

On exit: the number of iterations carried out by f11bec.

2: $\mathbf{stplhs}$ – double * Output

On exit: the current value of the left-hand side of the termination criterion used by f11bec.

3: $\mathbf{stprhs}$ – double * Output

On exit: the current value of the right-hand side of the termination criterion used by f11bec.

4: $\mathbf{anorm}$ – double * Output

On exit: if $\mathbf{iterm}=1$ in the previous call to f11bdc, then anorm contains ${‖A‖}_p$, where $p=1$, $2$ or $\infty$, either supplied or, in the case of $1$ or $\infty$, estimated by f11bec; otherwise $\mathbf{anorm}=0.0$.

5: $\mathbf{sigmax}$ – double * Output

On exit: if $\mathbf{iterm}=2$ in the previous call to f11bdc, the current estimate of the largest singular value ${\sigma }_1\left(\overline{A}\right)$ of the preconditioned iteration matrix, either when it has been supplied to f11bdc or it has been estimated by f11bec (see also Sections 3 and 5 in f11bdc); otherwise, $\mathbf{sigmax}=0.0$ is returned.

6: $\mathbf{work}\left[\mathbf{lwork}\right]$ – const double Communication Array

On entry: the array work as returned by f11bec (see also Sections 3 and 5 in f11bec).

7: $\mathbf{lwork}$ – Integer Input

On entry: the dimension of the array work (see also Section 5 in f11bdc).

Constraint: $\mathbf{lwork}\ge 100$.

Note: although the minimum value of lwork ensures the correct functioning of f11bfc, a larger value is required by the iterative solver f11bec (see also Section 5 in f11bdc).

8: $\mathbf{fail}$ – NagError * Input/Output

The NAG error argument (see Section 7 in the Introduction to the NAG Library CL Interface).

6 Error Indicators and Warnings

NE_ALLOC_FAIL

Dynamic memory allocation failed.
See Section 3.1.2 in the Introduction to the NAG Library CL Interface for further information.

NE_BAD_PARAM

On entry, argument $〈\mathit{\text{value}}〉$ had an illegal value.

NE_INT

On entry, $\mathbf{lwork}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{lwork}\ge 100$.

NE_INTERNAL_ERROR

An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG for assistance.
See Section 7.5 in the Introduction to the NAG Library CL Interface for further information.

NE_NO_LICENCE

Your licence key may have expired or may not have been installed correctly.
See Section 8 in the Introduction to the NAG Library CL Interface for further information.

NE_OUT_OF_SEQUENCE

f11bfc has been called out of sequence.

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example