# NAG Library Routine Document

## 1Purpose

x04eaf is an easy-to-use routine to print an integer matrix stored in a two-dimensional array.

## 2Specification

Fortran Interface
 Subroutine x04eaf ( diag, m, n, a, lda,
 Integer, Intent (In) :: m, n, a(lda,*), lda Integer, Intent (Inout) :: ifail Character (*), Intent (In) :: title Character (1), Intent (In) :: matrix, diag
#include <nagmk26.h>
 void x04eaf_ (const char *matrix, const char *diag, const Integer *m, const Integer *n, const Integer a[], const Integer *lda, const char *title, Integer *ifail, const Charlen length_matrix, const Charlen length_diag, const Charlen length_title)

## 3Description

x04eaf prints an integer matrix. It is an easy-to-use driver for x04ebf. The routine uses default values for the format in which numbers are printed, for labelling the rows and columns, and for output record length.
x04eaf will choose a format code such that numbers will be printed with the smallest I edit descriptor that is large enough to hold all the numbers to be printed.
The matrix is printed with integer row and column labels, and with a maximum record length of $80$.
The matrix is output to the unit defined by x04abf.

None.

## 5Arguments

1:     $\mathbf{matrix}$ – Character(1)Input
On entry: indicates the part of the matrix to be printed.
${\mathbf{matrix}}=\text{'G'}$
The whole of the rectangular matrix.
${\mathbf{matrix}}=\text{'L'}$
The lower triangle of the matrix, or the lower trapezium if the matrix has more rows than columns.
${\mathbf{matrix}}=\text{'U'}$
The upper triangle of the matrix, or the upper trapezium if the matrix has more columns than rows.
Constraint: ${\mathbf{matrix}}=\text{'G'}$, $\text{'L'}$ or $\text{'U'}$.
2:     $\mathbf{diag}$ – Character(1)Input
On entry: unless ${\mathbf{matrix}}=\text{'G'}$, diag must specify whether the diagonal elements of the matrix are to be printed.
${\mathbf{diag}}=\text{'B'}$
The diagonal elements of the matrix are not referenced and not printed.
${\mathbf{diag}}=\text{'U'}$
The diagonal elements of the matrix are not referenced, but are assumed all to be unity, and are printed as such.
${\mathbf{diag}}=\text{'N'}$
The diagonal elements of the matrix are referenced and printed.
If ${\mathbf{matrix}}=\text{'G'}$, then diag need not be set.
Constraint: if ${\mathbf{matrix}}\ne \text{'G'}$, ${\mathbf{diag}}=\text{'B'}$, $\text{'U'}$ or $\text{'N'}$.
3:     $\mathbf{m}$ – IntegerInput
4:     $\mathbf{n}$ – IntegerInput
On entry: the number of rows and columns of the matrix, respectively, to be printed.
If either m or n is less than $1$, x04eaf will exit immediately after printing title; no row or column labels are printed.
5:     $\mathbf{a}\left({\mathbf{lda}},*\right)$ – Integer arrayInput
Note: the second dimension of the array a must be at least $\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{n}}\right)$.
On entry: the matrix to be printed. Only the elements that will be referred to, as specified by arguments matrix and diag, need be set.
6:     $\mathbf{lda}$ – IntegerInput
On entry: the first dimension of the array a as declared in the (sub)program from which x04eaf is called.
Constraint: ${\mathbf{lda}}\ge \mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{m}}\right)$.
7:     $\mathbf{title}$ – Character(*)Input
On entry: a title to be printed above the matrix.
If , no title (and no blank line) will be printed.
If title contains more than $80$ characters, the contents of title will be wrapped onto more than one line, with the break after $80$ characters.
Any trailing blank characters in title are ignored.
8:     $\mathbf{ifail}$ – IntegerInput/Output
On entry: ifail must be set to $0$, . If you are unfamiliar with this argument you should refer to Section 3.4 in How to Use the NAG Library and its Documentation for details.
For environments where it might be inappropriate to halt program execution when an error is detected, the value  is recommended. If the output of error messages is undesirable, then the value $1$ is recommended. Otherwise, if you are not familiar with this argument, the recommended value is $0$. When the value  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).

## 6Error Indicators and Warnings

If on entry ${\mathbf{ifail}}=0$ or $-1$, explanatory error messages are output on the current error message unit (as defined by x04aaf).
Errors or warnings detected by the routine:
${\mathbf{ifail}}=1$
On entry, matrix is not valid: ${\mathbf{matrix}}=〈\mathit{\text{value}}〉$.
${\mathbf{ifail}}=2$
On entry, ${\mathbf{matrix}}=〈\mathit{\text{value}}〉$, but diag is not valid: ${\mathbf{diag}}=〈\mathit{\text{value}}〉$.
${\mathbf{ifail}}=3$
On entry, ${\mathbf{m}}=〈\mathit{\text{value}}〉$ and ${\mathbf{lda}}=〈\mathit{\text{value}}〉$.
Constraint: ${\mathbf{m}}\le {\mathbf{lda}}$.
${\mathbf{ifail}}=-99$
See Section 3.9 in How to Use the NAG Library and its Documentation for further information.
${\mathbf{ifail}}=-399$
Your licence key may have expired or may not have been installed correctly.
See Section 3.8 in How to Use the NAG Library and its Documentation for further information.
${\mathbf{ifail}}=-999$
Dynamic memory allocation failed.
See Section 3.7 in How to Use the NAG Library and its Documentation for further information.

Not applicable.

## 8Parallelism and Performance

x04eaf is not threaded in any implementation.

A call to x04eaf is equivalent to a call to x04ebf with the following argument values:
```
NCOLS = 80
INDENT = 0
LABROW = 'I'
LABCOL = 'I'
FORM = ' '```

## 10Example

This example calls x04eaf twice, first to print a $3$ by $5$ rectangular matrix, and then to print a $5$ by $5$ triangular matrix.

### 10.1Program Text

Program Text (x04eafe.f90)

None.

### 10.3Program Results

Program Results (x04eafe.r)