NAG FL Interface
f01vgf (dtfttr)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

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

On entry: specifies whether the normal RFP representation of $A$ or its transpose is stored.

$\mathbf{transr}=\text{'N'}$

The RFP representation of the matrix $A$ is stored.

$\mathbf{transr}=\text{'T'}$

The transpose of the RFP representation of the matrix $A$ is stored.

Constraint: $\mathbf{transr}=\text{'N'}$ or $\text{'T'}$.

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

On entry: specifies whether $A$ is upper or lower triangular.

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

$A$ is upper triangular.

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

$A$ is lower triangular.

Constraint: $\mathbf{uplo}=\text{'U'}$ or $\text{'L'}$.

3: $\mathbf{n}$ – Integer Input

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

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

4: $\mathbf{ar}\left(\mathbf{n}\times (\mathbf{n}+1)/2\right)$ – Real (Kind=nag_wp) array Input

On entry: the upper or lower $n\times n$ triangular matrix $A$ (as specified by uplo) in either normal or transposed RFP format (as specified by transr). The storage format is described in Section 3.3.3 in the F07 Chapter Introduction.

5: $\mathbf{a}(\mathbf{lda},*)$ – Real (Kind=nag_wp) array Output

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

On exit: the triangular matrix $A$.

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

6: $\mathbf{lda}$ – Integer Input

On entry: the first dimension of the array a as declared in the (sub)program from which f01vgf is called.

Constraint: $\mathbf{lda}\ge \max (1,\mathbf{n})$.

7: $\mathbf{info}$ – Integer Output

On exit: $\mathbf{info}=0$ unless the routine detects an error (see Section 6).

6 Error Indicators and Warnings

$\mathbf{info}<0$

If $\mathbf{info}=-i$, argument $i$ had an illegal value. An explanatory message is output, and execution of the program is terminated.

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example

10.1 Program Text

10.2 Program Data

10.3 Program Results