NAG FL Interface
f06fgf (dnegv)

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1 Purpose

f06fgf negates a real vector.

2 Specification

Fortran Interface
Subroutine f06fgf ( n, x, incx)
Integer, Intent (In) :: n, incx
Real (Kind=nag_wp), Intent (Inout) :: x(*)
C Header Interface
#include <nag.h>
void  f06fgf_ (const Integer *n, double x[], const Integer *incx)
The routine may be called by the names f06fgf or nagf_blas_dnegv.

3 Description

f06fgf performs the operation
where x is an n-element real vector scattered with stride incx.

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/Output
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.
On exit: the vector -x stored in the array elements used to supply the original vector x.
Intermediate elements of x are unchanged.
3: incx Integer Input
On entry: the increment in the subscripts of x between successive elements of x.
Constraint: incx>0.

6 Error Indicators and Warnings


7 Accuracy

Not applicable.

8 Parallelism and Performance

f06fgf is not threaded in any implementation.

9 Further Comments


10 Example