NAG Library Function Document

nag_pack_real_mat_print (x04ccc)

1

Purpose

2

Specification

3

Description

4

References

5

Arguments

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:    $\mathbf{uplo}$ – Nag_UploTypeInput

On entry: indicates the type of the matrix to be printed

$\mathbf{uplo}=\mathrm{Nag\_Lower}$

The matrix is lower triangular

$\mathbf{uplo}=\mathrm{Nag\_Upper}$

The matrix is upper triangular

Constraint: $\mathbf{uplo}=\mathrm{Nag\_Lower}$ or $\mathrm{Nag\_Upper}$.

3:    $\mathbf{diag}$ – Nag_DiagTypeInput

On entry: indicates whether the diagonal elements of the matrix are to be printed.

$\mathbf{diag}=\mathrm{Nag\_NonRefDiag}$

The diagonal elements of the matrix are not referenced and not printed.

$\mathbf{diag}=\mathrm{Nag\_UnitDiag}$

The diagonal elements of the matrix are not referenced, but are assumed all to be unity, and are printed as such.

$\mathbf{diag}=\mathrm{Nag\_NonUnitDiag}$

The diagonal elements of the matrix are referenced and printed.

Constraint: $\mathbf{diag}=\mathrm{Nag\_NonRefDiag}$, $\mathrm{Nag\_UnitDiag}$ or $\mathrm{Nag\_NonUnitDiag}$.

4:    $\mathbf{n}$ – IntegerInput

On entry: the order of the matrix to be printed.

If n is less than $1$, nag_pack_real_mat_print (x04ccc) will exit immediately after printing title; no row or column labels are printed.

5:    $\mathbf{a}\left[\mathit{dim}\right]$ – const doubleInput

Note: the dimension, dim, of the array a must be at least $\max \left(1,\mathbf{n}\times \left(\mathbf{n}+1\right)/2\right)$.

On entry: the matrix to be printed. Note that a must have space for the diagonal elements of the matrix, even if these are not stored.

The storage of elements $A_{ij}$ depends on the order and uplo arguments as follows:

• if $\mathbf{order}=\mathrm{Nag\_ColMajor}$ and $\mathbf{uplo}=\mathrm{Nag\_Upper}$,
            $A_{ij}$ is stored in $\mathbf{a}\left[\left(j-1\right)\times j/2+i-1\right]$, for $i\le j$;
• if $\mathbf{order}=\mathrm{Nag\_ColMajor}$ and $\mathbf{uplo}=\mathrm{Nag\_Lower}$,
            $A_{ij}$ is stored in $\mathbf{a}\left[\left(2n-j\right)\times \left(j-1\right)/2+i-1\right]$, for $i\ge j$;
• if $\mathbf{order}=\mathrm{Nag\_RowMajor}$ and $\mathbf{uplo}=\mathrm{Nag\_Upper}$,
            $A_{ij}$ is stored in $\mathbf{a}\left[\left(2n-i\right)\times \left(i-1\right)/2+j-1\right]$, for $i\le j$;
• if $\mathbf{order}=\mathrm{Nag\_RowMajor}$ and $\mathbf{uplo}=\mathrm{Nag\_Lower}$,
            $A_{ij}$ is stored in $\mathbf{a}\left[\left(i-1\right)\times i/2+j-1\right]$, for $i\ge j$.

If $\mathbf{diag}=\mathrm{Nag\_UnitDiag}$, the diagonal elements of $A$ are assumed to be $1$, and are not referenced; the same storage scheme is used whether $\mathbf{diag}=\mathrm{Nag\_NonUnitDiag}$ or $\mathbf{diag}=\mathrm{Nag\_UnitDiag}$.

6:    $\mathbf{title}$ – 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.

7:    $\mathbf{outfile}$ – 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.

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

The NAG error argument (see Section 3.7 in How to Use the NAG Library and its Documentation).

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_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.

7

Accuracy

8

Parallelism and Performance

9

Further Comments

ncols = 80
indent = 0
labrow = Nag_IntegerLabels
labcol = Nag_IntegerLabels
form = 0

10

Example