NAG Library Routine Document

F06WAF (DLANSF)

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:     TRANSR – CHARACTER(1)Input

On entry: specifies whether the RFP representation of $A$ is normal or transposed.

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

The matrix $A$ is stored in normal RFP format.

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

The matrix $A$ is stored in transposed RFP format.

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

3:     UPLO – CHARACTER(1)Input

On entry: specifies whether the upper or lower triangular part of $A$ is stored.

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

The upper triangular part of $A$ is stored.

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

The lower triangular part of $A$ is stored.

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

4:     N – INTEGERInput

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

When $\mathbf{N}=0$, F06WAF (DLANSF) returns zero.

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

5:     A($\mathbf{N}\times \left(\mathbf{N}+1\right)/2$) – REAL (KIND=nag_wp) arrayInput

On entry: the upper or lower triangular part (as specified by UPLO) of the $n$ by $n$ symmetric matrix $A$, in either normal or transposed RFP format, as described in Section 3.3.3 in the F07 Chapter Introduction.

6:     WORK($*$) – REAL (KIND=nag_wp) arrayWorkspace

Note: the dimension of the array WORK must be at least $\max \left(1,\mathbf{N}\right)$ if $\mathbf{NORM}=\text{'1'}$, $\text{'O'}$ or $\text{'I'}$, and at least $1$ otherwise.

6  Error Indicators and Warnings

7  Accuracy

8  Further Comments

9  Example

9.1  Program Text

Program Text (f06wafe.f90)

9.2  Program Data

Program Data (f06wafe.d)

9.3  Program Results

Program Results (f06wafe.r)