NAG Toolbox: nag_blast_isum (f16dl)

Purpose

Syntax

Description

References

Parameters

Compulsory Input Parameters

1:     $\mathrm{n}$ – int64int32nag_int scalar

$n$, the number of elements in $x$.

2:     $\mathrm{x}\left(1+\left(\mathbf{n}-1\right)\times \left|\mathbf{incx}\right|\right)$ – int64int32nag_int array

The $n$-element vector $x$.

If $\mathbf{incx}>0$, $x_{\mathit{i}}$ must be stored in $\mathbf{x}\left(\left(\mathit{i}-1\right)\times \left|\mathbf{incx}\right|+1\right)$, for $\mathit{i}=1,2,\dots ,\mathbf{n}$.

If $\mathbf{incx}<0$, $x_{\mathit{i}}$ must be stored in $\mathbf{x}\left(\left(\mathbf{n}-\mathit{i}\right)\times \left|\mathbf{incx}\right|+1\right)$, for $\mathit{i}=1,2,\dots ,\mathbf{n}$.

Intermediate elements of x are not referenced. If $\mathbf{n}=0$, x is not referenced.

3:     $\mathrm{incx}$ – int64int32nag_int scalar

The increment in the subscripts of x between successive elements of $x$.

Constraint: $\mathbf{incx}\ne 0$.

Optional Input Parameters

None.

Output Parameters

1:     $\mathrm{result}$ – int64int32nag_int scalar

The result of the function.

Error Indicators and Warnings

Accuracy

Further Comments

Example

Open in the MATLAB editor: f16dl_example

fprintf('f16dl example results\n\n');

% sum vector of integers x
n    = int64(5);
x    = [int64(1)  10  11  -2    9];
incx = int64(1);

xsum = f16dl(n, x, incx);

fprintf('sum(');
fprintf('%4d',x);
fprintf(') = %5d\n',xsum);

f16dl example results

sum(   1  10  11  -2   9) =    29