NAG FL Interface
f06klf (idrank)

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FL Name Style:

FL Specification Language:

1 Purpose

f06klf determines the index of the first negligible element of a real vector.

2 Specification

Fortran Interface
Function f06klf ( n, x, incx, tol)
Integer :: f06klf
Integer, Intent (In) :: n, incx
Real (Kind=nag_wp), Intent (In) :: x(*), tol
C Header Interface
#include <nag.h>
Integer  f06klf_ (const Integer *n, const double x[], const Integer *incx, const double *tol)
The routine may be called by the names f06klf or nagf_blas_idrank.

3 Description

f06klf finds the first element of the n-element real vector x for which
and returns the index k via the function name. If no such k exists, then the value n is returned. If a negative value of tol is supplied, the value of machine precision is used in place of tol.

4 References


5 Arguments

1: n Integer Input
On entry: n, the number of elements in x.
2: x(*) Real (Kind=nag_wp) array Input
Note: the dimension of the array x must be at least max(1, 1+(n-1) ×incx ) .
On entry: the n-element vector x. xi must be stored in x(1+(i-1)×incx), for i=1,2,,n.
Intermediate elements of x are not referenced.
3: incx Integer Input
On entry: the increment in the subscripts of x between successive elements of x.
Constraint: incx>0.
4: tol Real (Kind=nag_wp) Input
On entry: the value tol.

6 Error Indicators and Warnings


7 Accuracy

Not applicable.

8 Parallelism and Performance

Background information to multithreading can be found in the Multithreading documentation.
f06klf is not threaded in any implementation.

9 Further Comments


10 Example