NAG FL Interface
f06kcf (zddscl)

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1 Purpose

f06kcf multiplies a complex vector by a real diagonal matrix.

2 Specification

Fortran Interface
Subroutine f06kcf ( n, d, incd, x, incx)
Integer, Intent (In) :: n, incd, incx
Real (Kind=nag_wp), Intent (In) :: d(*)
Complex (Kind=nag_wp), Intent (Inout) :: x(*)
C Header Interface
#include <nag.h>
void  f06kcf_ (const Integer *n, const double d[], const Integer *incd, Complex x[], const Integer *incx)
The routine may be called by the names f06kcf or nagf_blas_zddscl.

3 Description

f06kcf performs the operation
where x is an n-element complex vector and D=diag(d) is a real diagonal matrix.
Equivalently, the routine performs the element-by-element product of the vectors x and d
xi=dixi,  i=1,2,,n.  

4 References


5 Arguments

1: n Integer Input
On entry: n, the number of elements in d and x.
2: d(*) Real (Kind=nag_wp) array Input
Note: the dimension of the array d must be at least max(1, 1+(n-1) ×|incd| ) .
On entry: the vector d.
If incd>0, di must be stored in d((i-1)×incd+1) , for i=1,2,,n.
If incd<0, di must be stored in d( 1-(n-i)×incd ) , for i=1,2,,n.
3: incd Integer Input
On entry: the increment in the subscripts of d between successive elements of d.
4: x(*) Complex (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 array x must contain the n-element vector x.
If incx>0, xi must be stored in x( 1+(i-1)×incx ) , for i=1,2,,n.
If incx<0, xi must be stored in x(1-(n-i)×incx) , for i=1,2,,n.
On exit: the updated vector x stored in the array elements used to supply the original vector x.
Intermediate elements of x are unchanged.
5: incx Integer Input
On entry: the increment in the subscripts of x between successive elements of x.

6 Error Indicators and Warnings


7 Accuracy

Not applicable.

8 Parallelism and Performance

Background information to multithreading can be found in the Multithreading documentation.
f06kcf makes calls to BLAS and/or LAPACK routines, which may be threaded within the vendor library used by this implementation. Consult the documentation for the vendor library for further information.
Please consult the X06 Chapter Introduction for information on how to control and interrogate the OpenMP environment used within this routine. Please also consult the Users' Note for your implementation for any additional implementation-specific information.

9 Further Comments


10 Example