NAG FL Interface
f06raf (dlange)

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1 Purpose

f06raf 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 m×n matrix.

2 Specification

Fortran Interface
Function f06raf ( norm, m, n, a, lda, work)
Real (Kind=nag_wp) :: f06raf
Integer, Intent (In) :: m, 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  f06raf_ (const char *norm, const Integer *m, const Integer *n, const double a[], const Integer *lda, double work[], const Charlen length_norm)
The routine may be called by the names f06raf or nagf_blas_dlange.

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,j|aij| (not a norm).
Constraint: norm='1', 'O', 'I', 'F', 'E' or 'M'.
2: m Integer Input
On entry: m, the number of rows of the matrix A.
When m=0, f06raf is set to zero.
Constraint: m0.
3: n Integer Input
On entry: n, the number of columns of the matrix A.
When n=0, f06raf is set to zero.
Constraint: n0.
4: a(lda,*) Real (Kind=nag_wp) array Input
Note: the second dimension of the array a must be at least n.
On entry: the m×n matrix A.
5: lda Integer Input
On entry: the first dimension of the array a as declared in the (sub)program from which f06raf is called.
Constraint: lda max(1,m) .
6: work(*) Real (Kind=nag_wp) array Workspace
Note: the dimension of the array work must be at least max(1,m) if norm='I', and at least 1 otherwise.

6 Error Indicators and Warnings

None.

7 Accuracy

Not applicable.

8 Parallelism and Performance

Background information to multithreading can be found in the Multithreading documentation.
f06raf is not threaded in any implementation.

9 Further Comments

None.

10 Example

None.