naginterfaces.library.blast.iamax_​val

naginterfaces.library.blast.iamax_val(x)

iamax_val computes, with respect to absolute value, the largest component of an integer vector, along with the index of that component.

For full information please refer to the NAG Library document for f16dq

https://support.nag.com/numeric/nl/nagdoc_30.3/flhtml/f16/f16dqf.html

Parameters

xint, 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

kint

Note: this argument represents an array index; the value returned will be base-1.

$k$, the index, from the set $\{1,2,\dots ,n\}$, of the largest component of $x$ with respect to absolute value. If $n\le 0$ on input then $k$ is returned as $0$.

iint

$i$, the largest component of $x$ with respect to absolute value. If $n\le 0$ on input then $i$ is returned as $0$.

Raises

NagValueError

(errno $-3$)

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

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

Notes

iamax_val computes, with respect to absolute value, the largest component, $i$, of an $n$-element integer vector $x$, and determines the smallest index, $k$, such that

$$i=\left|x_k\right|={max}_j\left|x_j\right|\text{.}$$

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