Integer, Intent (In)	::	m, n, lda
Integer, Intent (Inout)	::	ifail
Real (Kind=nag_wp), Intent (In)	::	a(lda,*)
Character (*), Intent (In)	::	title
Character (1), Intent (In)	::	matrix, diag

C Header Interface

#include <nag.h>

void	x04caf_ (const char matrix, const char diag, const Integer m, const Integer n, const double a[], const Integer lda, const char title, Integer *ifail, const Charlen length_matrix, const Charlen length_diag, const Charlen length_title)

The routine may be called by the names x04caf or nagf_file_print_matrix_real_gen.

3 Description

x04caf prints a real matrix. It is an easy-to-use driver for x04cbf. The routine uses default values for the format in which numbers are printed, for labelling the rows and columns, and for output record length.

x04caf will choose a format code such that numbers will be printed with an

F 8.4

, an

F 11.4

or a

1 PE 13.4

format. The

F 8.4

code is chosen if the sizes of all the matrix elements to be printed lie between

0.001

and

1.0

. The

F 11.4

code is chosen if the sizes of all the matrix elements to be printed lie between

0.001

and

9999.9999

. Otherwise the

1 PE 13.4

code is chosen.

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.

4 References

None.

5 Arguments

1: $matrix$ – Character(1) Input

On entry: indicates the part of the matrix to be printed.

$matrix ='G'$: The whole of the rectangular matrix.
$matrix ='L'$: The lower triangle of the matrix, or the lower trapezium if the matrix has more rows than columns.
$matrix ='U'$: The upper triangle of the matrix, or the upper trapezium if the matrix has more columns than rows.

Constraint:

matrix ='G'

'L'

'U'

2: $diag$ – Character(1) Input

On entry: unless

matrix ='G'

, diag must specify whether the diagonal elements of the matrix are to be printed.

$diag ='B'$: The diagonal elements of the matrix are not referenced and not printed.
$diag ='U'$: The diagonal elements of the matrix are not referenced, but are assumed all to be unity, and are printed as such.
$diag ='N'$: The diagonal elements of the matrix are referenced and printed.

matrix ='G'

, then diag need not be set.

Constraint: if

matrix \neq'G'

diag ='B'

'U'

'N'

3: $m$ – Integer Input

4: $n$ – Integer Input

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) array Input

Note: the second dimension of the array a must be at least

\max (1, n)

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: $lda$ – Integer Input

On entry: the first dimension of the array a as declared in the (sub)program from which x04caf is called.

Constraint:

lda \geq \max (1, m)

7: $title$ – Character(*) Input

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

title =' '

, 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: $ifail$ – Integer Input/Output

On entry: ifail must be set to

0

−1

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

1

is recommended. If message printing is undesirable, then the value

1

is recommended. Otherwise, the value

0

is recommended. When the value $- 1$ or $1$ is used it is essential to test the value of ifail on exit.

On exit:

ifail = 0

unless the routine detects an error or a warning has been flagged (see Section 6).

6 Error Indicators and Warnings

If on entry

ifail = 0

−1

, explanatory error messages are output on the current error message unit (as defined by x04aaf).

Errors or warnings detected by the routine:

$ifail = 1$: On entry, matrix is not valid: $matrix = ⟨ value ⟩$ .

$ifail = 2$: On entry, $matrix = ⟨ value ⟩$ , but diag is not valid: $diag = ⟨ value ⟩$ .

$ifail = 3$: On entry, $m = ⟨ value ⟩$ and $lda = ⟨ value ⟩$ .
Constraint: $m \leq lda$ .

$ifail = - 99$: 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.

$ifail = - 399$: 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.