NAG Library Routine Document

F06QFF

1  Purpose

2  Specification

3  Description

4  References

5  Parameters

1:     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:     M – INTEGERInput

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

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

3:     N – INTEGERInput

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

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

4:     A(LDA,$*$) – 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:     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:     B(LDB,$*$) – 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:     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  Further Comments

9  Example