NAG Library Routine Document

F06UPF

1  Purpose

2  Specification

3  Description

4  References

5  Parameters

1:     NORM – CHARACTER(1)Input

On entry: specifies the value to be returned.

$\mathbf{NORM}=\text{'1'}$ or $\text{'O'}$

The $1$-norm.

$\mathbf{NORM}=\text{'I'}$

The $\infty$-norm.

$\mathbf{NORM}=\text{'F'}$ or $\text{'E'}$

The Frobenius (or Euclidean) norm.

$\mathbf{NORM}=\text{'M'}$

The value ${\displaystyle \underset{i,j}{\max }}\left|a_{ij}\right|$ (not a norm).

Constraint: $\mathbf{NORM}=\text{'1'}$, $\text{'O'}$, $\text{'I'}$, $\text{'F'}$, $\text{'E'}$ or $\text{'M'}$.

2:     N – INTEGERInput

On entry: $n$, the order of the matrix $A$.

When $\mathbf{N}=0$, F06UPF returns zero.

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

3:     D($*$) – REAL (KIND=nag_wp) arrayInput

Note: the dimension of the array D must be at least $\max \left(1,\mathbf{N}\right)$.

On entry: the $n$ diagonal elements of the tridiagonal matrix $A$.

4:     E($*$) – COMPLEX (KIND=nag_wp) arrayInput

Note: the dimension of the array E must be at least $\max \left(1,\mathbf{N}-1\right)$.

On entry: the ($n-1$) subdiagonal or superdiagonal elements of the tridiagonal matrix $A$.

6  Error Indicators and Warnings

7  Accuracy

8  Further Comments

9  Example