NAG Library Function Document

nag_band_real_mat_print (x04cec)

1  Purpose

2  Specification

3  Description

4  References

5  Arguments

1:     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 3.2.1.3 in the Essential Introduction for a more detailed explanation of the use of this argument.

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

2:     m – IntegerInput

3:     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_real_mat_print (x04cec) will exit immediately after printing title; no row or column labels are printed.

4:     kl – IntegerInput

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

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

5:     ku – IntegerInput

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

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

6:     a[$\mathit{dim}$] – const doubleInput

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

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

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

7:     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:     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:     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:   fail – NagError *Input/Output

The NAG error argument (see Section 3.6 in the Essential Introduction).

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  for appending.

NE_NOT_CLOSE_FILE

Cannot close file .

NE_NOT_WRITE_FILE

Cannot open file  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