naginterfaces.library.blast.dsum

naginterfaces.library.blast.dsum(x)

dsum sums the elements of a real vector.

For full information please refer to the NAG Library document for f16el

https://www.nag.com/numeric/nl/nagdoc_29.3/flhtml/f16/f16elf.html

Parameters

xfloat, array-like, shape $\left(n\right)$

The $n$-element vector $x$.

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

If $n=0$, $x$ is not referenced.

Returns

sumxfloat

The sum of the elements of $x$.

Raises

NagValueError

(errno $-3$)

On entry, error in parameter $\text{incx}$.

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

Notes

dsum returns the sum

$$x_1+x_2+\cdots +x_n$$

of the elements of an $n$-element real vector $x$.

If $n\le 0$ on entry, dsum returns the value $0$.

References

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