NAG CL Interface
x04cfc (print_​matrix_​real_​band_​comp)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{order}$ – Nag_OrderType Input

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 3.1.3 in the Introduction to the NAG Library CL Interface for a more detailed explanation of the use of this argument.

Constraint: $\mathbf{order}=\mathrm{Nag\_RowMajor}$ or $\mathrm{Nag\_ColMajor}$.

2: $\mathbf{m}$ – Integer Input

3: $\mathbf{n}$ – 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 $1$, x04cfc will exit immediately after printing title; no row or column labels are printed.

4: $\mathbf{kl}$ – Integer Input

On entry: the number of subdiagonals of the band matrix $A$.

Constraint: $\mathbf{kl}\ge 0$.

5: $\mathbf{ku}$ – Integer Input

On entry: the number of superdiagonals of the band matrix $A$.

Constraint: $\mathbf{ku}\ge 0$.

6: $\mathbf{a}\left[\mathit{dim}\right]$ – const double Input

Note: the dimension, dim, of the array a must be at least

• $\max (1,\mathbf{pda}\times \mathbf{n})$ when $\mathbf{order}=\mathrm{Nag\_ColMajor}$;
• $\max (1,\mathbf{m}\times \mathbf{pda})$ 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 $j=\max (1,i-k_l),\dots ,\min (n,i+k_u)$, depends on the order argument as follows:

• if $\mathbf{order}=\mathrm{Nag\_ColMajor}$, $A_{ij}$ is stored as $\mathbf{a}\left[(j-1)\times \mathbf{pda}+\mathbf{ku}+i-j\right]$;
• if $\mathbf{order}=\mathrm{Nag\_RowMajor}$, $A_{ij}$ is stored as $\mathbf{a}\left[(i-1)\times \mathbf{pda}+\mathbf{kl}+j-i\right]$.

7: $\mathbf{pda}$ – Integer Input

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: $\mathbf{form}$ – const char * Input

On entry: a valid C format code. This should be of the form $\%\left[\mathit{flag}\right]ww.pp\left[\mathit{format}\text{ }\mathit{indicator}\right]$, where $\mathit{ww}.pp$ indicates that up to two digits may be used to specify the field width and precision respectively. Only % and $\mathit{format}\text{ }\mathit{indicator}$ must be present. $\mathit{flag}$ can be one of $-$, $+$, $<\text{space}>$ or # and $\mathit{format}\text{ }\mathit{indicator}$ can be e, E, f, g or G. Thus, possible formats include %f, %+23.15G, %.6e. form is used to print elements of the matrix $A$.

In addition, x04cfc chooses its own format code when form is NULL or $\mathbf{form}=\text{'}*\text{'}$.

$\mathbf{form}=\mathbf{NULL}$

x04cfc will choose a format code such that numbers will be printed with either a %8.4f, a %11.4f or a %13.4e format. The %8.4f code is chosen if the sizes of all the matrix elements to be printed lie between $0.001$ and $1.0$. The %11.4f code is chosen if the sizes of all the matrix elements to be printed lie between $0.001$ and $9999.9999$. Otherwise the %13.4e code is chosen.

$\mathbf{form}=\text{'}*\text{'}$

x04cfc 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.

Constraint: form must be of the form $\%\left[\mathit{flag}\right]ww.pp\left[\mathit{format}\text{ }\mathit{indicator}\right]$.

9: $\mathbf{title}$ – const char * Input

On entry: a title to be printed above the matrix, or name of the matrix.

If $\mathbf{title}=\mathbf{NULL}$, 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.

10: $\mathbf{labrow}$ – Nag_LabelType Input

On entry: indicates the type of labelling to be applied to the rows of the matrix.

$\mathbf{labrow}=\mathrm{Nag\_NoLabels}$

Prints no row labels.

$\mathbf{labrow}=\mathrm{Nag\_IntegerLabels}$

Prints integer row labels.

$\mathbf{labrow}=\mathrm{Nag\_CharacterLabels}$

Prints character labels, which must be supplied in array rlabs.

Constraint: $\mathbf{labrow}=\mathrm{Nag\_NoLabels}$, $\mathrm{Nag\_IntegerLabels}$ or $\mathrm{Nag\_CharacterLabels}$.

11: $\mathbf{rlabs}\left[\mathit{dim}\right]$ – const char * Input

Note: the dimension, dim, of the array rlabs must be at least

• $\mathbf{m}$ when $\mathbf{labrow}=\mathrm{Nag\_CharacterLabels}$;
• otherwise rlabs may be NULL.

On entry: if $\mathbf{labrow}=\mathrm{Nag\_CharacterLabels}$, rlabs must contain labels for the rows of the matrix; otherwise rlabs is not referenced and may be NULL.

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: $\mathbf{labcol}$ – Nag_LabelType Input

On entry: indicates the type of labelling to be applied to the columns of the matrix.

$\mathbf{labcol}=\mathrm{Nag\_NoLabels}$

Prints no column labels.

$\mathbf{labcol}=\mathrm{Nag\_IntegerLabels}$

Prints integer column labels.

$\mathbf{labcol}=\mathrm{Nag\_CharacterLabels}$

Prints character labels, which must be supplied in array clabs.

Constraint: $\mathbf{labcol}=\mathrm{Nag\_NoLabels}$, $\mathrm{Nag\_IntegerLabels}$ or $\mathrm{Nag\_CharacterLabels}$.

13: $\mathbf{clabs}\left[\mathit{dim}\right]$ – const char * Input

Note: the dimension, dim, of the array clabs must be at least

• $\mathbf{n}$ when $\mathbf{labcol}=\mathrm{Nag\_CharacterLabels}$;
• otherwise clabs may be NULL.

On entry: if $\mathbf{labcol}=\mathrm{Nag\_CharacterLabels}$, clabs must contain labels for the columns of the matrix; otherwise clabs is not referenced and may be NULL.

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 or equal to $0$ 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: $\mathbf{outfile}$ – 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.

17: $\mathbf{fail}$ – NagError * Input/Output

The NAG error argument (see Section 7 in the Introduction to the NAG Library CL Interface).

6 Error Indicators and Warnings

NE_ALLOC_FAIL

Memory allocation failed.

NE_BAD_PARAM

On entry, argument $⟨\mathit{\text{value}}⟩$ had an illegal value.

NE_COL_WIDTH

$⟨\mathit{\text{value}}⟩$ is not wide enough to hold at least one matrix column. $\mathbf{ncols}=⟨\mathit{\text{value}}⟩$ and $\mathbf{indent}=⟨\mathit{\text{value}}⟩$.

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_INVALID_FORMAT

The string $⟨\mathit{\text{value}}⟩$ has not been recognized as a valid format.

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.

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example