# NAG FL Interfacex04dff (print_​matrix_​complex_​band_​comp)

## ▸▿ Contents

Settings help

FL Name Style:

FL Specification Language:

## 1Purpose

x04dff prints a complex band matrix stored in a packed two-dimensional array.

## 2Specification

Fortran Interface
 Subroutine x04dff ( m, n, kl, ku, a, lda, form,
 Integer, Intent (In) :: m, n, kl, ku, lda, ncols, indent Integer, Intent (Inout) :: ifail Complex (Kind=nag_wp), Intent (In) :: a(lda,*) Character (*), Intent (In) :: form, title, rlabs(*), clabs(*) Character (1), Intent (In) :: usefrm, labrow, labcol
#include <nag.h>
 void x04dff_ (const Integer *m, const Integer *n, const Integer *kl, const Integer *ku, const Complex a[], const Integer *lda, const char *usefrm, const char *form, const char *title, const char *labrow, const char rlabs[], const char *labcol, const char clabs[], const Integer *ncols, const Integer *indent, Integer *ifail, const Charlen length_usefrm, const Charlen length_form, const Charlen length_title, const Charlen length_labrow, const Charlen length_rlabs, const Charlen length_labcol, const Charlen length_clabs)
The routine may be called by the names x04dff or nagf_file_print_matrix_complex_band_comp.

## 3Description

x04dff prints a complex band matrix stored in a packed two-dimensional array, using a format specifier supplied by you. The matrix is output to the unit defined by x04abf.

None.

## 5Arguments

1: $\mathbf{m}$Integer Input
2: $\mathbf{n}$Integer Input
On entry: the number of rows and columns of the band matrix, respectively, to be printed.
If either m or n is less than $1$, x04dff will exit immediately after printing title; no row or column labels are printed.
3: $\mathbf{kl}$Integer Input
On entry: the number of subdiagonals of the band matrix $A$.
Constraint: ${\mathbf{kl}}\ge 0$.
4: $\mathbf{ku}$Integer Input
On entry: the number of superdiagonals of the band matrix $A$.
Constraint: ${\mathbf{ku}}\ge 0$.
5: $\mathbf{a}\left({\mathbf{lda}},*\right)$Complex (Kind=nag_wp) array Input
Note: the second dimension of the array a must be at least $\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,\mathrm{min}\phantom{\rule{0.125em}{0ex}}\left({\mathbf{m}}+{\mathbf{ku}},{\mathbf{n}}\right)\right)$.
On entry: the band matrix to be printed.
The matrix is stored in rows $1$ to ${k}_{l}+{k}_{u}+1$, more precisely, the element ${A}_{ij}$ must be stored in
 $a(ku+1+i-j,j) for ​max(1,j-ku)≤i≤min(m,j+kl).$
6: $\mathbf{lda}$Integer Input
On entry: the first dimension of the array a as declared in the (sub)program from which x04dff is called.
Constraint: ${\mathbf{lda}}\ge {\mathbf{kl}}+{\mathbf{ku}}+1$.
7: $\mathbf{usefrm}$Character(1) Input
On entry: indicates how the value of form is to be used to print matrix elements, except in MATLAB mode where usefrm is ignored.
${\mathbf{usefrm}}=\text{'A'}$
The format code in form is assumed to contain a single real edit-descriptor which is to be used to print the real and imaginary parts of each complex number one above the other. Each row of the matrix is separated by a blank line, and any row labels are attached only to the real parts. This option means that about twice as many columns can be fitted into ncols characters than if any other usefrm option is used. A typical value of form for this usefrm option might be $\text{'}\mathrm{E13.4}\text{'}$, $\text{'}*\text{'}$ or .
${\mathbf{usefrm}}=\text{'B'}$
The format code in form is assumed to contain a single edit-descriptor such as $\text{'}\mathrm{E13.4}\text{'}$, $\text{'}*\text{'}$ or which is used to print the real and imaginary parts of each complex number separated by a comma, and surrounded by brackets. Thus a matrix element printed with this usefrm option might look like this: $\left(12.345,-11.323\right)$.
${\mathbf{usefrm}}=\text{'D'}$
The format code in form is used unaltered to print a complex number. This usefrm option allows you flexibility to specify exactly how the number is printed. With this option for usefrm and a suitable value for form it is possible, for example, to print a complex number in the form $\left(0.123+3.214i\right)$ or $\left(\text{0.123E−02},\text{0.234E−01}\right)$.
Constraint: ${\mathbf{usefrm}}=\text{'A'}$, $\text{'B'}$ or $\text{'D'}$.
8: $\mathbf{form}$Character(*) Input
On entry: describes the Fortran format code that is used in conjunction with usefrm for printing the elements of the matrix a. The format code may be any allowed on the system, whether it is standard Fortran or not. It may or may not be enclosed in brackets.
In addition, there are the following special codes which force x04dff to choose its own format code:
x04dff will choose a format code such that numbers will be printed with an F8.4, an F11.4 or a 1PE13.4 format. The F8.4 code is chosen if the sizes of the real and imaginary parts of all the matrix elements to be printed lie between $0.001$ and $1.0$. The F11.4 code is chosen if the sizes of all the numbers to be printed lie between $0.001$ and $9999.9999$. Otherwise the 1PE13.4 code is chosen.
${\mathbf{form}}=\text{'}*\text{'}$
x04dff will choose a format code such that numbers will be printed to as many significant digits as are necessary to distinguish between neighbouring machine numbers. Thus any two numbers that are stored with different internal representations should look different on output. Whether they do in fact look different will depend on the run-time library of the Fortran compiler in use.
By preceding the desired format code by the string ‘MATLAB’, x04dff will print the matrix such that it can be input into MATLAB, and title will be used as the name of the matrix.
More complicated values of form, to print a complex number in a desired form, may be used. See the description of argument usefrm for more details.
Examples of valid values for form are $\text{'}\mathrm{\left(F11.4\right)}\text{'}$, $\text{'}\mathrm{1P,2E13.5}\text{'}$, $\text{'}\mathrm{MATLABF11.4}\text{'}$, $\text{'}\mathrm{MATLAB*}\text{'}$.
Constraint: the character length of the format specifier in form must be $\text{}\le 80$.
9: $\mathbf{title}$Character(*) Input
On entry: a title to be printed above the matrix, or name of the matrix.
If , no title (and no blank line) will be printed.
If title contains more than ncols characters, the contents of title will be wrapped onto more than one line, with the break after ncols characters.
Any trailing blank characters in title are ignored.
If printing in MATLAB mode, title will be used as the name of the matrix.
10: $\mathbf{labrow}$Character(1) Input
On entry: indicates the type of labelling to be applied to the rows of the matrix, except in MATLAB mode where labrow is ignored.
${\mathbf{labrow}}=\text{'N'}$
Prints no row labels.
${\mathbf{labrow}}=\text{'I'}$
Prints integer row labels.
${\mathbf{labrow}}=\text{'C'}$
Prints character labels, which must be supplied in array rlabs.
Constraint: ${\mathbf{labrow}}=\text{'N'}$, $\text{'I'}$ or $\text{'C'}$.
11: $\mathbf{rlabs}\left(*\right)$Character(*) array Input
Note: the dimension of the array rlabs must be at least ${\mathbf{m}}$ if ${\mathbf{labrow}}=\text{'C'}$, and at least $1$ otherwise.
On entry: if ${\mathbf{labrow}}=\text{'C'}$, rlabs must contain labels for the rows of the matrix, except in MATLAB mode where rlabs is ignored.
Labels are right-justified when output, in a field which is as wide as necessary to hold the longest row label. Note that this field width is subtracted from the number of usable columns, ncols.
12: $\mathbf{labcol}$Character(1) Input
On entry: indicates the type of labelling to be applied to the columns of the matrix, except in MATLAB mode where labcol is ignored.
${\mathbf{labcol}}=\text{'N'}$
Prints no column labels.
${\mathbf{labcol}}=\text{'I'}$
Prints integer column labels.
${\mathbf{labcol}}=\text{'C'}$
Prints character labels, which must be supplied in array clabs.
Constraint: ${\mathbf{labcol}}=\text{'N'}$, $\text{'I'}$ or $\text{'C'}$.
13: $\mathbf{clabs}\left(*\right)$Character(*) array Input
Note: the dimension of the array clabs must be at least ${\mathbf{n}}$ if ${\mathbf{labcol}}=\text{'C'}$, and at least $1$ otherwise.
On entry: if ${\mathbf{labcol}}=\text{'C'}$, clabs must contain labels for the columns of the matrix, except in MATLAB mode where clabs is ignored.
Labels are right-justified when output. Any label that is too long for the column width, which is determined by form, is truncated.
14: $\mathbf{ncols}$Integer Input
On entry: the maximum output record length. If the number of columns of the matrix is too large to be accommodated in ncols characters, the matrix will be printed in parts, containing the largest possible number of matrix columns, and each part separated by a blank line.
ncols must be large enough to hold at least one column of the matrix using the format specifier in form. If a value less than $0$ or greater than $132$ is supplied for ncols, then the value $80$ is used instead.
15: $\mathbf{indent}$Integer Input
On entry: the number of columns by which the matrix (and any title and labels) should be indented. The effective value of ncols is reduced by indent columns. If a value less than $0$ or greater than ncols is supplied for indent, the value $0$ is used instead.
16: $\mathbf{ifail}$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).

## 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, ${\mathbf{kl}}=⟨\mathit{\text{value}}⟩$.
Constraint: ${\mathbf{kl}}\ge 0$.
${\mathbf{ifail}}=2$
On entry, ${\mathbf{ku}}=⟨\mathit{\text{value}}⟩$.
Constraint: ${\mathbf{ku}}\ge 0$.
${\mathbf{ifail}}=3$
On entry, ${\mathbf{lda}}<{\mathbf{kl}}+{\mathbf{ku}}+1$: ${\mathbf{lda}}=⟨\mathit{\text{value}}⟩$, ${\mathbf{kl}}=⟨\mathit{\text{value}}⟩$, ${\mathbf{ku}}=⟨\mathit{\text{value}}⟩$.
${\mathbf{ifail}}=4$
On entry, invalid usefrm: ${\mathbf{usefrm}}=⟨\mathit{\text{value}}⟩$.
${\mathbf{ifail}}=5$
The string $⟨\mathit{\text{value}}⟩$ has not been recognized as a valid format.
${\mathbf{ifail}}=6$
The string $⟨\mathit{\text{value}}⟩$ has not been recognized as a valid format.
${\mathbf{ifail}}=7$
On entry, either labrow or labcol is not valid: ${\mathbf{labrow}}=⟨\mathit{\text{value}}⟩$, ${\mathbf{labcol}}=⟨\mathit{\text{value}}⟩$.
${\mathbf{ifail}}=8$
On entry, ${\mathbf{ncols}}-{\mathbf{indent}}$ is not wide enough to hold at least one matrix column: ${\mathbf{ncols}}=⟨\mathit{\text{value}}⟩$, ${\mathbf{indent}}=⟨\mathit{\text{value}}⟩$.
${\mathbf{ifail}}=-99$
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.

Not applicable.

## 8Parallelism and Performance

x04dff is not threaded in any implementation.

None.

## 10Example

The example program calls x04dff three times, to print band matrices of different orders and bandwidths; various options for labelling and formatting are illustrated.

### 10.1Program Text

Program Text (x04dffe.f90)

None.

### 10.3Program Results

Program Results (x04dffe.r)