C Library Functions - dot (3)

NAME

dot(3f) - [M_datapac:VECTOR_OPERATION] compute a dot product of two vectors

Synopsis
Description
Input Options
Output Options
Examples
Author
Maintainer
License

SYNOPSIS

subroutine dot(A,B,Imin,Imax,Parpro,Dotpro)

    real(kind=wp),intent(in)  :: A(:), B(:), Parpro
    real(kind=wp),intent(out) :: Dotpro
    integer,intent(in)        :: Imax, Imin

DESCRIPTION

To compute the dot product between 2 vectors A and B only elements IMIN through IMAX of the 2 vectors are considered. The computed dot product is added to the input value PARPRO to yield a final answer for DOTPRO.
Note Fortran now has a dot product intrinsic called DOT_PRODUCT(3f).

INPUT OPTIONS

A First vector

B Second vector

Imin First index in A and B to consider

Imax Last index in A and B to consider

Parpro Initial value to add the dot product to

OUTPUT OPTIONS

Dotpro Dot product of A and B.

EXAMPLES

Sample program:

   program demo_dot
   use M_datapac, only : dot, label
   real, dimension(3) :: a, b
   real :: dotpro , parpro
   integer i , imax , imin
      call label(’dot’)
      a = [ 1.0, 2.0, 3.0 ]
      b = [ 4.0, 5.0, 6.0 ]
      imin=1
      imax=size(a)
      parpro=0.0
      call dot(a,b,imin,imax,parpro,dotpro)
      write(*,*)a
      write(*,*)b
      write(*,*)dotpro, dot_product(a,b), dotpro == dot_product(a,b)
   end program demo_dot

Results:

1.000000 2.000000 3.000000 4.000000 5.000000 6.000000 32.00000 32.00000 T

AUTHOR

The original DATAPAC library was written by James Filliben of the Statistical Engineering Division, National Institute of Standards and Technology.

MAINTAINER

John Urban, 2022.05.31

LICENSE

CC0-1.0

Nemo Release 3.1

dot (3)

February 23, 2025

Generated by manServer 1.08 from 74f5735d-7fe0-41a3-901b-8011589012da using man macros.

A	First vector
B	Second vector
Imin	First index in A and B to consider
Imax	Last index in A and B to consider
Parpro	Initial value to add the dot product to