# v_qrmult

## PURPOSE

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

## SYNOPSIS

function q=v_qrmult(q1,q2)

## DESCRIPTION

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

     Inputs:   q1(4m,n)  Two real quaternions arrays. Either array can
               q2(4n,r)  also be a scalar quaternion.

     Outputs:   q(4m,r)  Matrix product of q1 and q2

## CROSS-REFERENCE INFORMATION

This function calls:

- v_qrdotmult V_QRDOTMULT multiplies together two real quaternions arrays q=[q1,q2]
- v_rotqr2mr V_ROTQR2MR converts a matrix of real quaternion vectors to quaternion matrices

This function is called by:

## SOURCE CODE

    0001 function q=v_qrmult(q1,q2)
    0002 %V_QRMULT multiplies together two real quaternions matrices q=[q1,q2]
    0003 %
    0004 % Inputs:   q1(4m,n)  Two real quaternions arrays. Either array can
    0005 %           q2(4n,r)  also be a scalar quaternion.
    0006 %
    0007 % Outputs:   q(4m,r)  Matrix product of q1 and q2
    0008
    0009 %      Copyright (C) Mike Brookes 2000-2012
    0010 %      Version: $Id: v_qrmult.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 s1=size(q1);
    0031 s2=size(q2);
    0032 if isequal(s1,[4 1])
    0033     q=v_qrdotmult(repmat(q1,s2(1)/4,s2(2)),q2);
    0034 elseif isequal(s2,[4 1])
    0035     q=v_qrdotmult(q1,repmat(q2,s1(1)/4,s1(2)));
    0036 else
    0037     q=v_rotqr2mr(q1)*q2;
    0038 end