naginterfaces.library.blas.zgthr

naginterfaces.library.blas.zgthr(y, indx)

zgthr gathers specified (usually nonzero) elements of a complex vector $y$ in full storage form into a sparse complex vector $x$ in compressed form.

For full information please refer to the NAG Library document for f06gu

https://www.nag.com/numeric/nl/nagdoc_29.3/flhtml/f06/f06guf.html

Parameters

ycomplex, array-like, shape $(max\left(indx\right))$

The vector $y$. Only elements corresponding to indices in $indx$ are accessed.

indxint, array-like, shape $\left(\text{nz}\right)$

$indx$ must contain the set of indices $J$.

Returns

xcomplex, ndarray, shape $\left(\text{nz}\right)$

The compressed vector $x$.

Notes

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

References

Dodson, D S, Grimes, R G and Lewis, J G, 1991, Sparse extensions to the Fortran basic linear algebra subprograms, ACM Trans. Math. Software (17), 253–263