NAG FL Interface
f06qxf (dgesrc)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{side}$ – Character(1) Input

On entry: specifies whether $A$ is operated on from the left or the right.

$\mathbf{side}=\text{'L'}$

$A$ is pre-multiplied from the left.

$\mathbf{side}=\text{'R'}$

$A$ is post-multiplied from the right.

Constraint: $\mathbf{side}=\text{'L'}$ or $\text{'R'}$.

2: $\mathbf{pivot}$ – Character(1) Input

On entry: specifies the plane rotated by $P_k$.

$\mathbf{pivot}=\text{'V'}$ (variable pivot)

$P_k$ rotates the $\left(k,k+1\right)$ plane.

$\mathbf{pivot}=\text{'T'}$ (top pivot)

$P_k$ rotates the $\left(k_1,k+1\right)$ plane.

$\mathbf{pivot}=\text{'B'}$ (bottom pivot)

$P_k$ rotates the $\left(k,k_2\right)$ plane.

Constraint: $\mathbf{pivot}=\text{'V'}$, $\text{'T'}$ or $\text{'B'}$.

3: $\mathbf{direct}$ – Character(1) Input

On entry: specifies the sequence direction.

$\mathbf{direct}=\text{'F'}$ (forward sequence)

$P=P_{k_2-1}\cdots P_{k_1+1}{P}_{k_1}$.

$\mathbf{direct}=\text{'B'}$ (backward sequence)

$P=P_{k_1}{P}_{k_1+1}\cdots P_{k_2-1}$.

Constraint: $\mathbf{direct}=\text{'F'}$ or $\text{'B'}$.

4: $\mathbf{m}$ – Integer Input

On entry: $m$, the number of rows of the matrix $A$.

If $\mathbf{m}<1$, an immediate return is effected.

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

5: $\mathbf{n}$ – Integer Input

On entry: $n$, the number of columns of the matrix $A$.

If $\mathbf{n}<1$, an immediate return is effected.

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

6: $\mathbf{k1}$ – Integer Input

7: $\mathbf{k2}$ – Integer Input

On entry: the values $k_1$ and $k_2$.

If $\mathbf{k1}<1$ or $\mathbf{k2}\le \mathbf{k1}$, or $\mathbf{side}=\text{'L'}$ and $\mathbf{k2}>\mathbf{m}$, or $\mathbf{side}=\text{'R'}$ and $\mathbf{k2}>\mathbf{n}$, an immediate return is effected.

8: $\mathbf{c}\left(\mathbf{k2}-1\right)$ – Real (Kind=nag_wp) array Input

On entry: $\mathbf{c}\left(\mathit{k}\right)$ must hold $c_{\mathit{k}}$, the cosine of the rotation $P_{\mathit{k}}$, for $\mathit{k}={\mathit{k}}_1,\dots ,{\mathit{k}}_2-1$.

9: $\mathbf{s}\left(\mathbf{k2}-1\right)$ – Real (Kind=nag_wp) array Input

On entry: $\mathbf{s}\left(\mathit{k}\right)$ must hold $s_{\mathit{k}}$, the sine of the rotation $P_{\mathit{k}}$, for $\mathit{k}={\mathit{k}}_1,\dots ,{\mathit{k}}_2-1$.

10: $\mathbf{a}\left(\mathbf{lda},*\right)$ – Real (Kind=nag_wp) array Input/Output

Note: the second dimension of the array a must be at least $\mathbf{n}$.

On entry: the $m$ by $n$ matrix $A$.

On exit: the transformed matrix $A$.

11: $\mathbf{lda}$ – Integer Input

On entry: the first dimension of the array a as declared in the (sub)program from which f06qxf is called.

Constraint: $\mathbf{lda}\ge \max \left(1,\mathbf{m}\right)$.

6 Error Indicators and Warnings

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example