naginterfaces.library.blas.idamax

naginterfaces.library.blas.idamax(x)

idamax computes the index of the absolutely largest component of a real vector.

For full information please refer to the NAG Library document for f06jl

https://support.nag.com/numeric/nl/nagdoc_30.3/flhtml/f06/f06jlf.html

Parameters

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

The $n$-element vector $x$.

Returns

imaxint

The index of the absolutely largest component of the real vector, $x$.

Raises

NagValueError

(errno $3$)

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

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

Notes

No equivalent traditional C interface for this routine exists in the NAG Library.

idamax returns the smallest index $i$ such that

$$\left|x_i\right|={max}_j\left|x_j\right|$$

where $x$ is an $n$-element real vector.

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