naginterfaces.library.blas.ddscl

naginterfaces.library.blas.ddscl(d, x)

ddscl multiplies a real vector by a real diagonal matrix.

For full information please refer to the NAG Library document for f06fc

https://support.nag.com/numeric/nl/nagdoc_30.2/flhtml/f06/f06fcf.html

Parameters

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

The vector $d$.

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

The array $x$ must contain the $n$-element vector $x$.

Returns

xfloat, ndarray, shape $\left(n\right)$

The updated vector $x$.

Notes

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

ddscl performs the operation

$$x\leftarrow Dx$$

where $x$ is an $n$-element real vector and $D=diag\left(d\right)$ is a real diagonal matrix.

Equivalently, the function performs the element-by-element product of the vectors $x$ and $d$

$$x_i=d_i{x}_i\text{,}i=1,2,\dots ,n\text{.}$$