NAG FL Interface
f06rmf (dlanhs)

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FL Name Style:

FL Specification Language:

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×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 <nag.h>
double  f06rmf_ (const char *norm, const Integer *n, const double a[], const Integer *lda, double work[], const Charlen length_norm)
The routine may be called by the names f06rmf or nagf_blas_dlanhs.

3 Description


4 References


5 Arguments

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

6 Error Indicators and Warnings


7 Accuracy

Not applicable.

8 Parallelism and Performance

Background information to multithreading can be found in the Multithreading documentation.
f06rmf is not threaded in any implementation.

9 Further Comments


10 Example