NAG Library Routine Document

X04CAF

1  Purpose

2  Specification

3  Description

4  References

5  Parameters

1:     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:     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:     M – INTEGERInput

4:     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 $1$, X04CAF will exit immediately after printing TITLE; no row or column labels are printed.

5:     A(LDA,$*$) – REAL (KIND=nag_wp) arrayInput

Note: the second dimension of the array A must be at least $\max \left(1,\mathbf{N}\right)$.

On entry: the matrix to be printed. Only the elements that will be referred to, as specified by parameters MATRIX and DIAG, need be set.

6:     LDA – INTEGERInput

On entry: the first dimension of the array A as declared in the (sub)program from which X04CAF is called.

Constraint: $\mathbf{LDA}\ge \max \left(1,\mathbf{M}\right)$.

7:     TITLE – CHARACTER(*)Input

On entry: a title to be printed above the matrix.

If $\mathbf{TITLE}=\text{' '}$, 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:     IFAIL – INTEGERInput/Output

On entry: IFAIL must be set to $0$, $-1\text{ or }1$. If you are unfamiliar with this parameter you should refer to Section 3.3 in the Essential Introduction for details.

For environments where it might be inappropriate to halt program execution when an error is detected, the value $-1\text{ or }1$ is recommended. If the output of error messages is undesirable, then the value $1$ is recommended. Otherwise, if you are not familiar with this parameter, the recommended value is $0$. When the value $-\mathbf{1}\text{ or }\mathbf{1}$ 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,

$\mathbf{MATRIX}\ne \text{'G'}$, $\text{'L'}$ or $\text{'U'}$.

$\mathbf{IFAIL}=2$

On entry,

$\mathbf{MATRIX}=\text{'L'}$ or $\text{'U'}$, but $\mathbf{DIAG}\ne \text{'N'}$, $\text{'U'}$ or $\text{'B'}$.

$\mathbf{IFAIL}=3$

On entry,

$\mathbf{LDA}<\mathbf{M}$.

7  Accuracy

8  Further Comments

NCOLS = 80
INDENT = 0
LABROW = 'I'
LABCOL = 'I'
FORM = ' '

9  Example

9.1  Program Text

Program Text (x04cafe.f90)

9.2  Program Data

9.3  Program Results

Program Results (x04cafe.r)