NAG FL Interface
g03ehf (cluster_​hier_​dendrogram)

1 Purpose

2 Specification

3 Description

Figure 1

4 References

5 Arguments

1: $\mathbf{orient}$ – Character(1) Input

On entry: indicates which orientation the dendrogram is to take.

$\mathbf{orient}=\text{'N'}$

The end points of the dendrogram are to the north.

$\mathbf{orient}=\text{'S'}$

The end points of the dendrogram are to the south.

$\mathbf{orient}=\text{'E'}$

The end points of the dendrogram are to the east.

$\mathbf{orient}=\text{'W'}$

The end points of the dendrogram are to the west.

Constraint: $\mathbf{orient}=\text{'N'}$, $\text{'S'}$, $\text{'E'}$ or $\text{'W'}$.

2: $\mathbf{n}$ – Integer Input

On entry: the number of objects in the cluster analysis.

Constraint: $\mathbf{n}>2$.

3: $\mathbf{dord}\left(\mathbf{n}\right)$ – Real (Kind=nag_wp) array Input

On entry: the array dord as output by g03ecf. dord contains the distances, in dendrogram order, at which clustering takes place.

Constraint: $\mathbf{dord}\left(\mathbf{n}\right)\ge \mathbf{dord}\left(\mathit{i}\right)$, for $\mathit{i}=1,2,\dots ,\mathbf{n}-1$.

4: $\mathbf{dmin}$ – Real (Kind=nag_wp) Input

On entry: the clustering distance at which the dendrogram begins.

Constraint: $\mathbf{dmin}\ge 0.0$.

5: $\mathbf{dstep}$ – Real (Kind=nag_wp) Input

On entry: the distance represented by one symbol of the dendrogram.

Constraint: $\mathbf{dstep}>0.0$.

6: $\mathbf{nsym}$ – Integer Input

On entry: the number of character positions used in the dendrogram. Hence the clustering distance at which the dendrogram terminates is given by $\mathbf{dmin}+\mathbf{nsym}\times \mathbf{dstep}$.

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

7: $\mathbf{c}\left(\mathbf{lenc}\right)$ – Character(*) array Output

Note:  the length of each element of c must be at least $3\times \mathbf{n}$ if $\mathbf{orient}=\text{'N'}$ or $\text{'S'}$, or at least nsym if $\mathbf{orient}=\text{'E'}$ or $\text{'W'}$.

On exit: the elements of c contain consecutive lines of the dendrogram.

8: $\mathbf{lenc}$ – Integer Input

On entry: the dimension of the array c as declared in the (sub)program from which g03ehf is called.

Constraints:

• if $\mathbf{orient}=\text{'N'}$ or $\text{'S'}$, $\mathbf{lenc}\ge \mathbf{nsym}$;
• if $\mathbf{orient}=\text{'E'}$ or $\text{'W'}$, $\mathbf{lenc}\ge \mathbf{n}$.

9: $\mathbf{ifail}$ – Integer Input/Output

On entry: ifail must be set to $0$, $-1$ or $1$ to set behaviour on detection of an error; these values have no effect when no error is detected.

A value of $0$ causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of $-1$ means that an error message is printed while a value of $1$ means that it is not.

If halting is not appropriate, the value $-1$ or $1$ is recommended. If message printing is undesirable, then the value $1$ is recommended. Otherwise, the value $0$ is recommended. When the value $-\mathbf{1}$ or $\mathbf{1}$ is used it is essential to test the value of ifail on exit.

On exit: $\mathbf{ifail}=\mathbf{0}$ unless the routine detects an error or a warning has been flagged (see Section 6).

6 Error Indicators and Warnings

$\mathbf{ifail}=1$

On entry, $\mathbf{dmin}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{dmin}\ge 0.0$.

On entry, $\mathbf{dstep}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{dstep}>0.0$.

On entry, $\mathbf{lenc}=〈\mathit{\text{value}}〉$ and $\mathbf{orient}=\text{'E'}$ or $\text{'W'}$.
Constraint: if $\mathbf{orient}=\text{'E'}$ or $\text{'W'}$, $\mathbf{lenc}\ge \mathbf{n}$.

On entry, $\mathbf{lenc}=〈\mathit{\text{value}}〉$ and $\mathbf{orient}=\text{'N'}$ or $\text{'S'}$.
Constraint: if $\mathbf{orient}=\text{'N'}$ or $\text{'S'}$, $\mathbf{lenc}\ge \mathbf{nsym}$.

On entry, $\mathbf{n}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{n}>2$.

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

On entry, $\mathbf{orient}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{orient}=\text{'N'}$, $\text{'S'}$, $\text{'E'}$ or $\text{'W'}$.

On entry, the number of characters that can be stored in each element of c is insufficient for the requested orientation.

$\mathbf{ifail}=2$

On entry, $\mathbf{dord}\left(i\right)>\mathbf{dord}\left(\mathbf{n}\right)$, $i<\mathbf{n}$.

$\mathbf{ifail}=-99$

An unexpected error has been triggered by this routine. Please contact NAG.

See Section 7 in the Introduction to the NAG Library FL Interface for further information.

$\mathbf{ifail}=-399$

Your licence key may have expired or may not have been installed correctly.

See Section 8 in the Introduction to the NAG Library FL Interface for further information.

$\mathbf{ifail}=-999$

Dynamic memory allocation failed.

See Section 9 in the Introduction to the NAG Library FL Interface for further information.

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example

10.1 Program Text

10.2 Program Data

10.3 Program Results