NAG CL Interface
x04dec (print_​matrix_​complex_​band)

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 $1$, x04dec 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 Complex Input

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: $\mathbf{pda}$ – 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: $\mathbf{title}$ – 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 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_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
cmplxform = Nag_AboveForm

10 Example