NAG Library Routine Document

f06jkf (dzasum)

 Contents

    1  Purpose
    7  Accuracy
    10  Example

1
Purpose

f06jkf (dzasum) returns the sum of the absolute values of the real and imaginary parts of the elements in a complex vector.

2
Specification

Fortran Interface
Function f06jkf ( n, x, incx)
Real (Kind=nag_wp):: f06jkf
Integer, Intent (In):: n, incx
Complex (Kind=nag_wp), Intent (In):: x(*)
C Header Interface
#include nagmk26.h
double  f06jkf_ (const Integer *n, const Complex x[], const Integer *incx)
The routine may be called by its BLAS name dzasum.

3
Description

f06jkf (dzasum) returns the norm
Rex1+Imx1++Rexn+Imxn  
of the n-element complex vector x scattered with stride incx, via the function name.

4
References

Lawson C L, Hanson R J, Kincaid D R and Krogh F T (1979) Basic linear algebra supbrograms for Fortran usage ACM Trans. Math. Software 5 308–325

5
Arguments

1:     n – IntegerInput
On entry: n, the number of elements in x.
2:     x* – Complex (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.

6
Error Indicators and Warnings

None.

7
Accuracy

Not applicable.

8
Parallelism and Performance

f06jkf (dzasum) is not threaded in any implementation.

9
Further Comments

None.

10
Example

None.
© The Numerical Algorithms Group Ltd, Oxford, UK. 2017