NAG CL Interface
f11zbc (real_​symm_​sort)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{n}$ – Integer Input

On entry: $n$, the order of the matrix $A$.

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

2: $\mathbf{nnz}$ – Integer * Input/Output

On entry: the number of elements supplied in the array a.

Constraint: $\mathbf{nnz}\ge 0$.

On exit: the number of elements with unique row and column indices.

3: $\mathbf{a}\left[\mathit{dim}\right]$ – double Input/Output

Note: the dimension, dim, of the array a must be at least $\max (1,\mathbf{nnz})$.

On entry: the nonzero elements of the lower triangular part of the real matrix $A$. These may be in any order and there may be multiple nonzero elements with the same row and column indices.

On exit: the lower triangular nonzero elements ordered by increasing row index, and by increasing column index within each row. Each nonzero element has a unique row and column index.

4: $\mathbf{irow}\left[\mathit{dim}\right]$ – Integer Input/Output

Note: the dimension, dim, of the array irow must be at least $\max (1,\mathbf{nnz})$.

On entry: the row indices corresponding to the elements supplied in the array a.

Constraint: $1\le \mathbf{irow}\left[\mathit{i}\right]\le \mathbf{n}$, for $\mathit{i}=0,1,\dots ,\mathbf{nnz}-1$.

On exit: the first nnz elements contain the row indices corresponding to the elements returned in the array a.

5: $\mathbf{icol}\left[\mathit{dim}\right]$ – Integer Input/Output

Note: the dimension, dim, of the array icol must be at least $\max (1,\mathbf{nnz})$.

On entry: the column indices corresponding to the elements supplied in the array a.

Constraint: $1\le \mathbf{icol}\left[\mathit{i}\right]\le \mathbf{irow}\left[\mathit{i}\right]$, for $\mathit{i}=0,1,\dots ,\mathbf{nnz}-1$.

On exit: the first nnz elements contain the column indices corresponding to the elements returned in the array a.

6: $\mathbf{dup}$ – Nag_SparseSym_Dups Input

On entry: indicates how elements in a with duplicate row and column indices are to be treated.

$\mathbf{dup}=\mathrm{Nag\_SparseSym\_RemoveDups}$

Duplicate entries are removed, only the first entry is kept.

$\mathbf{dup}=\mathrm{Nag\_SparseSym\_SumDups}$

The relevant values in a are summed.

$\mathbf{dup}=\mathrm{Nag\_SparseSym\_FailDups}$

The function fails with $\mathbf{fail}\mathbf{.}\mathbf{code}=$ NE_NON_ZERO_DUP on detecting a duplicate.

Constraint: $\mathbf{dup}=\mathrm{Nag\_SparseSym\_RemoveDups}$, $\mathrm{Nag\_SparseSym\_SumDups}$ or $\mathrm{Nag\_SparseSym\_FailDups}$.

7: $\mathbf{zero}$ – Nag_SparseSym_Zeros Input

On entry: indicates how elements in a with zero values are to be treated.

$\mathbf{zero}=\mathrm{Nag\_SparseSym\_RemoveZeros}$

The entries are removed.

$\mathbf{zero}=\mathrm{Nag\_SparseSym\_KeepZeros}$

The entries are kept.

$\mathbf{zero}=\mathrm{Nag\_SparseSym\_FailZeros}$

The function fails with $\mathbf{fail}\mathbf{.}\mathbf{code}=$ NE_ZERO_COEFF on detecting a zero.

Constraint: $\mathbf{zero}=\mathrm{Nag\_SparseSym\_RemoveZeros}$, $\mathrm{Nag\_SparseSym\_KeepZeros}$ or $\mathrm{Nag\_SparseSym\_FailZeros}$.

8: $\mathbf{istr}\left[\mathbf{n}+1\right]$ – Integer Output

On exit: $\mathbf{istr}\left[\mathit{i}-1\right]-1$, for $\mathit{i}=1,2,\dots ,\mathbf{n}$, is the starting address in the arrays a, irow and icol of row $i$ of the matrix $A$. $\mathbf{istr}\left[\mathbf{n}\right]-1$ is the address of the last element in a plus one.

9: $\mathbf{fail}$ – 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_ARG_LT

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

On entry, $\mathbf{nnz}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{nnz}\ge 0$.

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_NON_ZERO_DUP

On entry, a duplicate entry has been found in row $\mathit{I}$ and column $\mathit{J}$: $\mathit{I}=⟨\mathit{\text{value}}⟩$, $\mathit{J}=⟨\mathit{\text{value}}⟩$.

NE_SYMM_MATRIX

On entry, $i=⟨\mathit{\text{value}}⟩$, $\mathbf{icol}\left[i-1\right]=⟨\mathit{\text{value}}⟩$ and $\mathbf{irow}\left[i-1\right]=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{icol}\left[i-1\right]\ge 1$ and $\mathbf{icol}\left[i-1\right]\le \mathbf{irow}\left[i-1\right]$.

On entry, $i=⟨\mathit{\text{value}}⟩$, $\mathbf{irow}\left[i-1\right]=⟨\mathit{\text{value}}⟩$ and $\mathbf{n}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{irow}\left[i-1\right]\ge 1$ and $\mathbf{irow}\left[i-1\right]\le \mathbf{n}$.

NE_ZERO_COEFF

On entry, a zero entry has been found in row $\mathit{I}$ and column $\mathit{J}$: $\mathit{I}=⟨\mathit{\text{value}}⟩$, $\mathit{J}=⟨\mathit{\text{value}}⟩$.

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example

10.1 Program Text

10.2 Program Data

10.3 Program Results