F06UMF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual

NAG Library Routine Document

F06UMF

Note:  before using this routine, please read the Users' Note for your implementation to check the interpretation of bold italicised terms and other implementation-dependent details.

 Contents

    1  Purpose
    7  Accuracy
    10  Example

1  Purpose

F06UMF 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 complex n by n upper Hessenberg matrix.

2  Specification

FUNCTION F06UMF ( NORM, N, A, LDA, WORK)
REAL (KIND=nag_wp) F06UMF
INTEGER  N, LDA
REAL (KIND=nag_wp)  WORK(*)
COMPLEX (KIND=nag_wp)  A(LDA,*)
CHARACTER(1)  NORM

3  Description

None.

4  References

None.

5  Parameters

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, F06UMF returns zero.
Constraint: N0.
3:     ALDA* – COMPLEX (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 F06UMF 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

Not applicable.

9  Further Comments

None.

10  Example

None.

F06UMF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual

© The Numerical Algorithms Group Ltd, Oxford, UK. 2015