?dotu

Syntax

FORTRAN 77:

res = cdotu(n, x, incx, y, incy)

res = zdotu(n, x, incx, y, incy)

FORTRAN 95:

res = dotu(x, y)

Include Files

• FORTRAN 77: mkl_blas.fi
• Fortran 95: blas.f90
• C: mkl_blas.h

Description

The ?dotu routines perform a vector-vector reduction operation defined as

where x_i and y_i are elements of complex vectors x and y.

Input Parameters

n

INTEGER. Specifies the number of elements in vectors x and y.

x

COMPLEX for cdotu

DOUBLE COMPLEX for zdotu

Array, DIMENSION at least (1 + (n -1)*abs(incx)).

incx

INTEGER. Specifies the increment for the elements of x.

y

COMPLEX for cdotu

DOUBLE COMPLEX for zdotu

Array, DIMENSION at least (1 + (n -1)*abs(incy)).

incy

INTEGER. Specifies the increment for the elements of y.

Output Parameters

res

COMPLEX for cdotu

DOUBLE COMPLEX for zdotu

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

Fortran 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 Fortran 95 Interface Conventions.

Specific details for the routine dotu interface are the following:

x

Holds the vector with the number of elements n.

y

Holds the vector with the number of elements n.