NAG Library Function Document

nag_sparse_nsym_basic_diagnostic (f11bfc)

1  Purpose

2  Specification

3  Description

4  References

5  Arguments

1:    $\mathbf{itn}$ – Integer *Output

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

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

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

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

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

4:    $\mathbf{anorm}$ – double *Output

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

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

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

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

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

7:    $\mathbf{lwork}$ – IntegerInput

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

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

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

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

The NAG error argument (see Section 3.6 in the Essential Introduction).

6  Error Indicators and Warnings

NE_ALLOC_FAIL

Dynamic memory allocation failed.
See Section 3.2.1.2 in the Essential Introduction 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.

An unexpected error has been triggered by this function. Please contact NAG.
See Section 3.6.6 in the Essential Introduction for further information.

NE_NO_LICENCE

Your licence key may have expired or may not have been installed correctly.
See Section 3.6.5 in the Essential Introduction for further information.

NE_OUT_OF_SEQUENCE

nag_sparse_nsym_basic_diagnostic (f11bfc) has been called out of sequence.

7  Accuracy

8  Parallelism and Performance

9  Further Comments

10  Example