F06KLF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual

NAG Library Routine Document

F06KLF

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
    9  Example

1  Purpose

F06KLF determines the index of the first negligible element of a real vector.

2  Specification

FUNCTION F06KLF ( N, X, INCX, TOL)
INTEGER F06KLF
INTEGER  N, INCX
REAL (KIND=nag_wp)  X(*), TOL

3  Description

F06KLF finds the first element of the n-element real vector x for which
xk+1tolmaxx1,,xk
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

None.

5  Parameters

1:     N – INTEGERInput
On entry: n, the number of elements in x.
2:     X(*) – REAL (KIND=nag_wp) arrayInput
Note: the dimension of the array X must be at least max1, 1+N-1 ×INCX .
On entry: the n-element vector x. xi must be stored in X1+i-1×INCX, for i=1,2,,N.
Intermediate elements of X are not referenced.
3:     INCX – INTEGERInput
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

None.

7  Accuracy

Not applicable.

8  Further Comments

None.

9  Example

None.

F06KLF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual

© The Numerical Algorithms Group Ltd, Oxford, UK. 2012