NAG Library Routine Document

X04DEF

1  Purpose

2  Specification

3  Description

4  References

5  Parameters

1:     M – INTEGERInput

2:     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 $1$, X04DEF will exit immediately after printing TITLE; no row or column labels are printed.

3:     KL – INTEGERInput

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

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

4:     KU – INTEGERInput

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

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

5:     A(LDA,$*$) – COMPLEX (KIND=nag_wp) arrayInput

Note: the second dimension of the array A must be at least $\max \left(1,\min \left(\mathbf{M}+\mathbf{KU},\mathbf{N}\right)\right)$.

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

$$\mathbf{A}\left(k_u+1+i-j,j\right)\text{\hspace{1em} for }\max \left(1,j-k_u\right)\le i\le \min \left(m,j+k_l\right)\text{.}$$

6:     LDA – INTEGERInput

On entry: the first dimension of the array A as declared in the (sub)program from which X04DEF is called.

Constraint: $\mathbf{LDA}\ge \mathbf{KL}+\mathbf{KU}+1$.

7:     TITLE – CHARACTER(*)Input

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

If $\mathbf{TITLE}=\text{' '}$, 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 – INTEGERInput/Output

On entry: IFAIL must be set to $0$, $-1\text{ or }1$. If you are unfamiliar with this parameter you should refer to Section 3.3 in the Essential Introduction for details.

For environments where it might be inappropriate to halt program execution when an error is detected, the value $-1\text{ or }1$ is recommended. If the output of error messages is undesirable, then the value $1$ is recommended. Otherwise, if you are not familiar with this parameter, the recommended value is $0$. When the value $-\mathbf{1}\text{ or }\mathbf{1}$ 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).

6  Error Indicators and Warnings

$\mathbf{IFAIL}=1$

On entry,

$\mathbf{KL}<0$.

$\mathbf{IFAIL}=2$

On entry,

$\mathbf{KU}<0$.

$\mathbf{IFAIL}=3$

On entry,

$\mathbf{LDA}<\mathbf{KL}+\mathbf{KU}+1$.

7  Accuracy

8  Further Comments

NCOLS = 80
INDENT = 0
LABROW = 'I'
LABCOL = 'I'
FORM = ' '
USEFRM = 'A' 

9  Example

9.1  Program Text

Program Text (x04defe.f90)

9.2  Program Data

9.3  Program Results

Program Results (x04defe.r)