# v_qrdotmult

## PURPOSE

V_QRDOTMULT multiplies together two real quaternions arrays q=[q1,q2]

## SYNOPSIS

function q=v_qrdotmult(q1,q2)

## DESCRIPTION

    V_QRDOTMULT multiplies together two real quaternions arrays q=[q1,q2]

     Inputs:  q1(4n,...)
              q2(4n,...)   Two real quaternion arrays of equal size

     Outputs: q(4n,...)    The Hadamard product (i.e. .*) of the input arrays

          Copyright (C) Mike Brookes 2000-2012
          Version: $Id: v_qrdotmult.m 10865 2018-09-21 17:22:45Z dmb $

       VOICEBOX is a MATLAB toolbox for speech processing.
       Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
       This program is free software; you can redistribute it and/or modify
       it under the terms of the GNU Lesser General Public License as published by
       the Free Software Foundation; either version 3 of the License, or
       (at your option) any later version.

       This program is distributed in the hope that it will be useful,
       but WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
       GNU Lesser General Public License for more details.

       You can obtain a copy of the GNU Lesser General Public License from
       https://www.gnu.org/licenses/ .

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

## CROSS-REFERENCE INFORMATION

This function calls:

This function is called by:

- v_qrmult V_QRMULT multiplies together two real quaternions matrices q=[q1,q2]

## SOURCE CODE

    0001 function q=v_qrdotmult(q1,q2)
    0002 %V_QRDOTMULT multiplies together two real quaternions arrays q=[q1,q2]
    0003 %
    0004 % Inputs:  q1(4n,...)
    0005 %          q2(4n,...)   Two real quaternion arrays of equal size
    0006 %
    0007 % Outputs: q(4n,...)    The Hadamard product (i.e. .*) of the input arrays
    0008 %
    0009 %      Copyright (C) Mike Brookes 2000-2012
    0010 %      Version: $Id: v_qrdotmult.m 10865 2018-09-21 17:22:45Z dmb $
    0011 %
    0012 %   VOICEBOX is a MATLAB toolbox for speech processing.
    0013 %   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
    0014 %
    0015 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    0016 %   This program is free software; you can redistribute it and/or modify
    0017 %   it under the terms of the GNU Lesser General Public License as published by
    0018 %   the Free Software Foundation; either version 3 of the License, or
    0019 %   (at your option) any later version.
    0020 %
    0021 %   This program is distributed in the hope that it will be useful,
    0022 %   but WITHOUT ANY WARRANTY; without even the implied warranty of
    0023 %   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    0024 %   GNU Lesser General Public License for more details.
    0025 %
    0026 %   You can obtain a copy of the GNU Lesser General Public License from
    0027 %   https://www.gnu.org/licenses/ .
    0028 %
    0029 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    0030 persistent a b c
    0031 if isempty(a)
    0032     a=[1 2 3 4 2 1 4 3 3 4 1 2 4 3 2 1];
    0033     b=[1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4];
    0034     c=[2 3 4 7 12 14];
    0035 end
    0036 s=size(q1);
    0037 qa=reshape(q1,4,[]);
    0038 qb=reshape(q2,4,[]);
    0039 q=qa(a,:).*qb(b,:);
    0040 q(c,:)=-q(c,:);
    0041 q=reshape(sum(reshape(q,4,[]),1),s);