F16DLF (PDF version)
F16 Chapter Contents
F16 Chapter Introduction
NAG Library Manual

NAG Library Routine Document

F16DLF

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
    2  Specification
    3  Description
    4  References
    5  Parameters
    6  Error Indicators and Warnings
    7  Accuracy
    8  Further Comments
+− 9  Example

1  Purpose

F16DLF sums the elements of an integer vector.

2  Specification

FUNCTION F16DLF ( N, X, INCX)
INTEGER F16DLF
INTEGER  N, X(1+(N-1)*ABS(INCX)), INCX

3  Description

F16DLF returns the sum
x1 + x2 + ⋯ + xn
of the elements of an n-element integer vector x, via the function name.
If N≤0 on entry, F16DLF immediately returns the value 0.

4  References

Basic Linear Algebra Subprograms Technical (BLAST) Forum (2001) Basic Linear Algebra Subprograms Technical (BLAST) Forum Standard University of Tennessee, Knoxville, Tennessee http://www.netlib.org/blas/blast-forum/blas-report.pdf

5  Parameters

1:     N – INTEGERInput
On entry: n, the number of elements in x.
2:     X(1+N-1×INCX) – INTEGER arrayInput
On entry: the vector x. Element xi is stored in Xi-1×INCX+1, for i=1,2,…,n.
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

If INCX=0, an error message is printed and program execution is terminated.

7  Accuracy

The BLAS standard requires accurate implementations which avoid unnecessary over/underflow (see Section 2.7 of Basic Linear Algebra Subprograms Technical (BLAST) Forum (2001)).

8  Further Comments

None.

9  Example

This example computes the sum of the elements of
x = 1,10,11,-2,9T .

9.1  Program Text

Program Text (f16dlfe.f90)

9.2  Program Data

Program Data (f16dlfe.d)

9.3  Program Results

Program Results (f16dlfe.r)

F16DLF (PDF version)
F16 Chapter Contents
F16 Chapter Introduction
NAG Library Manual
© The Numerical Algorithms Group Ltd, Oxford, UK. 2012