# NAG C Library Function Document

## 1Purpose

nag_band_complx_mat_print (x04dec) is an easy-to-use function to print a Complex band matrix.

## 2Specification

 #include #include
 void nag_band_complx_mat_print (Nag_OrderType order, Integer m, Integer n, Integer kl, Integer ku, const Complex a[], Integer pda, const char *title, const char *outfile, NagError *fail)

## 3Description

nag_band_complx_mat_print (x04dec) prints a Complex band matrix stored in packed form. It is an easy-to-use driver for nag_band_complx_mat_print_comp (x04dfc). The function uses default values for the format in which numbers are printed, for labelling the rows and columns, and for output record length.
nag_band_complx_mat_print (x04dec) will choose a format code such that numbers will be printed with a $%8.4\mathrm{f}$, a $%11.4\mathrm{f}$ or a $%13.4\mathrm{e}$ format. The $%8.4\mathrm{f}$ code is chosen if the sizes of all the matrix elements to be printed lie between $0.001$ and $1.0$. The $%11.4\mathrm{f}$ code is chosen if the sizes of all the matrix elements to be printed lie between $0.001$ and $9999.9999$. Otherwise the $%13.4\mathrm{e}$ code is chosen. The chosen code is used to print each complex element of the matrix with the real part above the imaginary part.
The matrix is printed with integer row and column labels, and with a maximum record length of $80$.
The matrix is output to the file specified by outfile or, by default, to standard output.

None.

## 5Arguments

1:    $\mathbf{order}$Nag_OrderTypeInput
On entry: the order argument specifies the two-dimensional storage scheme being used, i.e., row-major ordering or column-major ordering. C language defined storage is specified by ${\mathbf{order}}=\mathrm{Nag_RowMajor}$. See Section 3.3.1.3 in How to Use the NAG Library and its Documentation for a more detailed explanation of the use of this argument.
Constraint: ${\mathbf{order}}=\mathrm{Nag_RowMajor}$ or $\mathrm{Nag_ColMajor}$.
2:    $\mathbf{m}$IntegerInput
3:    $\mathbf{n}$IntegerInput
On entry: the number of rows and columns of the band matrix, respectively, to be printed.
If either m or n is less than $1$, nag_band_complx_mat_print (x04dec) will exit immediately after printing title; no row or column labels are printed.
4:    $\mathbf{kl}$IntegerInput
On entry: the number of subdiagonals of the band matrix $A$.
Constraint: ${\mathbf{kl}}\ge 0$.
5:    $\mathbf{ku}$IntegerInput
On entry: the number of superdiagonals of the band matrix $A$.
Constraint: ${\mathbf{ku}}\ge 0$.
6:    $\mathbf{a}\left[\mathit{dim}\right]$const ComplexInput
Note: the dimension, dim, of the array a must be at least
• $\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{pda}}×{\mathbf{n}}\right)$ when ${\mathbf{order}}=\mathrm{Nag_ColMajor}$;
• $\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{m}}×{\mathbf{pda}}\right)$ when ${\mathbf{order}}=\mathrm{Nag_RowMajor}$.
On entry: the band matrix to be printed.
This is stored as a notional two-dimensional array with row elements or column elements stored contiguously. The storage of elements ${A}_{ij}$, for row $i=1,\dots ,m$ and column $j=\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,i-{k}_{l}\right),\dots ,\mathrm{min}\phantom{\rule{0.125em}{0ex}}\left(n,i+{k}_{u}\right)$, depends on the order argument as follows:
• if ${\mathbf{order}}=\mathrm{Nag_ColMajor}$, ${A}_{ij}$ is stored as ${\mathbf{a}}\left[\left(j-1\right)×{\mathbf{pda}}+{\mathbf{ku}}+i-j\right]$;
• if ${\mathbf{order}}=\mathrm{Nag_RowMajor}$, ${A}_{ij}$ is stored as ${\mathbf{a}}\left[\left(i-1\right)×{\mathbf{pda}}+{\mathbf{kl}}+j-i\right]$.
7:    $\mathbf{pda}$IntegerInput
On entry: the stride separating row or column elements (depending on the value of order) of the matrix $A$ in the array a.
Constraint: ${\mathbf{pda}}\ge {\mathbf{kl}}+{\mathbf{ku}}+1$.
8:    $\mathbf{title}$const char *Input
On entry: a title to be printed above the matrix.
If ${\mathbf{title}}=\mathbf{NULL}$, 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.
9:    $\mathbf{outfile}$const char *Input
On entry: the name of a file to which output will be directed. If outfile is NULL the output will be directed to standard output.
10:  $\mathbf{fail}$NagError *Input/Output
The NAG error argument (see Section 3.7 in How to Use the NAG Library and its Documentation).

## 6Error Indicators and Warnings

NE_ALLOC_FAIL
Memory allocation failed.
On entry, argument $〈\mathit{\text{value}}〉$ had an illegal value.
NE_INTERNAL_ERROR
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG for assistance.
NE_NOT_APPEND_FILE
Cannot open file $〈\mathit{\text{value}}〉$ for appending.
NE_NOT_CLOSE_FILE
Cannot close file $〈\mathit{\text{value}}〉$.
NE_NOT_WRITE_FILE
Cannot open file $〈\mathit{\text{value}}〉$ for writing.

Not applicable.

## 8Parallelism and Performance

nag_band_complx_mat_print (x04dec) is not threaded in any implementation.

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