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

ddoti computes the scalar product of a sparse real vector, stored in compressed form, with a real vector.

For full information please refer to the NAG Library document for f06er

xfloat, array-like, shape

The nonzero elements of the sparse vector .

indxint, array-like, shape

must contain the index of in the sparse vector , for .

yfloat, array-like, shape

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


The scalar product of the sparse real vector, , with the real vector .


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

ddoti returns the value of the scalar product

where is a sparse real vector, stored in compressed form and is a real vector in full storage format.


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