NAG Library Routine Document

f06rmf  (dlanhs)

 Contents

    1  Purpose
    7  Accuracy
    10  Example

1
Purpose

f06rmf returns, via the function name, the value of the 1-norm, the -norm, the Frobenius norm, or the maximum absolute value of the elements of a real n by n upper Hessenberg matrix.

2
Specification

Fortran Interface
Function f06rmf ( norm, n, a, lda, work)
Real (Kind=nag_wp):: f06rmf
Integer, Intent (In):: n, lda
Real (Kind=nag_wp), Intent (In):: a(lda,*)
Real (Kind=nag_wp), Intent (Inout):: work(*)
Character (1), Intent (In):: norm
C Header Interface
#include nagmk26.h
double  f06rmf_ ( const char *norm, const Integer *n, const double a[], const Integer *lda, double work[], const Charlen length_norm)

3
Description

None.

4
References

None.

5
Arguments

1:     norm – Character(1)Input
On entry: specifies the value to be returned.
norm='1' or 'O'
The 1-norm.
norm='I'
The -norm.
norm='F' or 'E'
The Frobenius (or Euclidean) norm.
norm='M'
The value maxi,jaij (not a norm).
Constraint: norm='1', 'O', 'I', 'F', 'E' or 'M'.
2:     n – IntegerInput
On entry: n, the order of the matrix A.
When n=0, f06rmf returns zero.
Constraint: n0.
3:     alda* – Real (Kind=nag_wp) arrayInput
Note: the second dimension of the array a must be at least n.
On entry: the n by n upper Hessenberg matrix A; elements of the array below the first subdiagonal are not referenced.
4:     lda – IntegerInput
On entry: the first dimension of the array a as declared in the (sub)program from which f06rmf is called.
Constraint: lda max1,n .
5:     work* – Real (Kind=nag_wp) arrayWorkspace
Note: the dimension of the array work must be at least max1,n  if norm='I', and at least 1 otherwise.

6
Error Indicators and Warnings

None.

7
Accuracy

Not applicable.

8
Parallelism and Performance

f06rmf is not threaded in any implementation.

9
Further Comments

None.

10
Example

None.
© The Numerical Algorithms Group Ltd, Oxford, UK. 2017