NAG Library Routine Document

F06QFF

1  Purpose

2  Specification

3  Description

4  References

5  Parameters

1:     $\mathrm{MATRIX}$ – CHARACTER(1)Input

On entry: the matrix type.

$\mathbf{MATRIX}=\text{'G'}$

General matrix.

$\mathbf{MATRIX}=\text{'U'}$

Upper trapezoidal matrix (upper triangular if $m=n$).

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

Lower trapezoidal matrix (lower triangular if $m=n$).

Constraint: $\mathbf{MATRIX}=\text{'G'}$, $\text{'U'}$ or $\text{'L'}$.

2:     $\mathrm{M}$ – INTEGERInput

On entry: $m$, the number of rows of the matrices $A$ and $B$.

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

3:     $\mathrm{N}$ – INTEGERInput

On entry: $n$, the number of columns of the matrices $A$ and $B$.

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

4:     $\mathrm{A}\left(\mathbf{LDA},*\right)$ – REAL (KIND=nag_wp) arrayInput

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

On entry: the $m$ by $n$ general or trapezoidal matrix $A$.

• If $\mathbf{MATRIX}=\text{'U'}$, $A$ is upper trapezoidal and the elements of the array below the diagonal are not referenced.
• If $\mathbf{MATRIX}=\text{'L'}$, $A$ is lower trapezoidal and the elements of the array above the diagonal are not referenced.

5:     $\mathrm{LDA}$ – INTEGERInput

On entry: the first dimension of the array A as declared in the (sub)program from which F06QFF is called.

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

6:     $\mathrm{B}\left(\mathbf{LDB},*\right)$ – REAL (KIND=nag_wp) arrayOutput

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

On exit: the $m$ by $n$ general or trapezoidal matrix $B$.

• If $\mathbf{MATRIX}=\text{'U'}$, $B$ is upper trapezoidal and the elements of the array below the diagonal are not referenced.
• If $\mathbf{MATRIX}=\text{'L'}$, $B$ is lower trapezoidal and the elements of the array above the diagonal are not referenced.

7:     $\mathrm{LDB}$ – INTEGERInput

On entry: the first dimension of the array B as declared in the (sub)program from which F06QFF is called.

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

6  Error Indicators and Warnings

7  Accuracy

8  Parallelism and Performance

9  Further Comments

10  Example