# naginterfaces.library.blas.dgthr¶

naginterfaces.library.blas.dgthr(y, indx)[source]

dgthr gathers specified (usually nonzero) elements of a real vector in full storage form into a sparse real vector in compressed form.

For full information please refer to the NAG Library document for f06eu

https://www.nag.com/numeric/nl/nagdoc_28.7/flhtml/f06/f06euf.html

Parameters
yfloat, array-like, shape

The vector . Only elements corresponding to indices in are accessed.

indxint, array-like, shape

must contain the index , for , which is to be gathered into .

Returns
xfloat, ndarray, shape

The compressed vector .

Notes

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

dgthr gathers the specified elements of a vector, , in full storage form, into , the equivalent sparse vector compressed form.

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