NAG Library Function Document

nag_sparse_herm_precon_ichol_solve (f11jpc)

1

Purpose

2

Specification

3

Description

4

References

5

Arguments

1:    $\mathbf{n}$ – IntegerInput

On entry: $n$, the order of the matrix $M$. This must be the same value as was supplied in the preceding call to nag_sparse_herm_chol_fac (f11jnc).

Constraint: $\mathbf{n}\ge 1$.

2:    $\mathbf{a}\left[\mathbf{la}\right]$ – const ComplexInput

On entry: the values returned in the array a by a previous call to nag_sparse_herm_chol_fac (f11jnc).

3:    $\mathbf{la}$ – IntegerInput

On entry: the dimension of the arrays a, irow and icol. This must be the same value supplied in the preceding call to nag_sparse_herm_chol_fac (f11jnc).

4:    $\mathbf{irow}\left[\mathbf{la}\right]$ – const IntegerInput

5:    $\mathbf{icol}\left[\mathbf{la}\right]$ – const IntegerInput

6:    $\mathbf{ipiv}\left[\mathbf{n}\right]$ – const IntegerInput

7:    $\mathbf{istr}\left[\mathbf{n}+1\right]$ – const IntegerInput

On entry: the values returned in arrays irow, icol, ipiv and istr by a previous call to nag_sparse_herm_chol_fac (f11jnc).

8:    $\mathbf{check}$ – Nag_SparseSym_CheckDataInput

On entry: specifies whether or not the input data should be checked.

$\mathbf{check}=\mathrm{Nag\_SparseSym\_Check}$

Checks are carried out on the values of n, irow, icol, ipiv and istr.

$\mathbf{check}=\mathrm{Nag\_SparseSym\_NoCheck}$

None of these checks are carried out.

Constraint: $\mathbf{check}=\mathrm{Nag\_SparseSym\_Check}$ or $\mathrm{Nag\_SparseSym\_NoCheck}$.

9:    $\mathbf{y}\left[\mathbf{n}\right]$ – const ComplexInput

On entry: the right-hand side vector $y$.

10:  $\mathbf{x}\left[\mathbf{n}\right]$ – ComplexOutput

On exit: the solution vector $x$.

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

The NAG error argument (see Section 3.7 in How to Use the NAG Library and its Documentation).

6

Error Indicators and Warnings

NE_ALLOC_FAIL

Dynamic memory allocation failed.
See Section 2.3.1.2 in How to Use the NAG Library and its Documentation for further information.

NE_BAD_PARAM

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

NE_INT

On entry, $\mathbf{n}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{n}\ge 1$.

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 2.7.6 in How to Use the NAG Library and its Documentation for further information.

NE_INVALID_ROWCOL_PIVOT

Check that a, irow, icol, ipiv and istr have not been corrupted between calls to nag_sparse_herm_chol_fac (f11jnc) and nag_sparse_herm_precon_ichol_solve (f11jpc).

NE_INVALID_SCS

Check that a, irow, icol, ipiv and istr have not been corrupted between calls to nag_sparse_herm_chol_fac (f11jnc) and nag_sparse_herm_precon_ichol_solve (f11jpc).

NE_INVALID_SCS_PRECOND

Check that a, irow, icol, ipiv and istr have not been corrupted between calls to nag_sparse_herm_chol_fac (f11jnc) and nag_sparse_herm_precon_ichol_solve (f11jpc).

NE_NO_LICENCE

Your licence key may have expired or may not have been installed correctly.
See Section 2.7.5 in How to Use the NAG Library and its Documentation for further information.

NE_NOT_STRICTLY_INCREASING

Check that a, irow, icol, ipiv and istr have not been corrupted between calls to nag_sparse_herm_chol_fac (f11jnc) and nag_sparse_herm_precon_ichol_solve (f11jpc).

7

Accuracy

8

Parallelism and Performance

9

Further Comments

9.1

Timing

10

Example

10.1

Program Text

Program Text (f11jpce.c)

10.2

Program Data

Program Data (f11jpce.d)

10.3

Program Results

Program Results (f11jpce.r)