Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

ID 766686
Date 3/31/2023
Public

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?doti

Computes the dot product of a compressed sparse real vector by a full-storage real vector.

Syntax

res = sdoti(nz, x, indx, y )

res = ddoti(nz, x, indx, y )

res = doti(x, indx, y)

Include Files
  • mkl.fi, blas.f90
Description

The ?doti routines return the dot product of x and y defined as

res = x(1)*y(indx(1)) + x(2)*y(indx(2)) +...+ x(nz)*y(indx(nz))

where the triple (nz, x, indx) defines a sparse real vector stored in compressed form, and y is a real vector in full storage form. The functions reference only the elements of y whose indices are listed in the array indx. The values in indx must be distinct.

Input Parameters
nz

INTEGER. The number of elements in x and indx .

x

REAL for sdoti

DOUBLE PRECISION for ddoti

Array, size at least nz.

indx

INTEGER. Specifies the indices for the elements of x.

Array, size at least nz.

y

REAL for sdoti

DOUBLE PRECISION for ddoti

Array, size at least max(indx(i)).

Output Parameters
res

REAL for sdoti

DOUBLE PRECISION for ddoti

Contains the dot product of x and y, if nz is positive. Otherwise, res contains 0.

BLAS 95 Interface Notes

Routines in Fortran 95 interface have fewer arguments in the calling sequence than their FORTRAN 77 counterparts. For general conventions applied to skip redundant or reconstructible arguments, see BLAS 95 Interface Conventions.

Specific details for the routine doti interface are the following:

x

Holds the vector with the number of elements nz.

indx

Holds the vector with the number of elements nz.

y

Holds the vector with the number of elements nz.