# v_rotqr2qc

## PURPOSE

V_ROTQR2QC converts a matrix of real quaternion vectors into complex form

## SYNOPSIS

function qc=v_rotqr2qc(qr)

## DESCRIPTION

    V_ROTQR2QC converts a matrix of real quaternion vectors into complex form

     Inputs:

         QR(4m,...)   array of real-valued quaternions

     Outputs:

         QC(2m,...)   array of complex-valued quaternions

     The real-valued quaternion [r a b c]' becomes [r+j*b  a+j*c]'

## CROSS-REFERENCE INFORMATION

This function calls:

- v_rotqr2ro ROTQR2RO converts a real quaternion to a 3x3 rotation matrix

This function is called by:

## SOURCE CODE

    0001 function qc=v_rotqr2qc(qr)
    0002 %V_ROTQR2QC converts a matrix of real quaternion vectors into complex form
    0003 %
    0004 % Inputs:
    0005 %
    0006 %     QR(4m,...)   array of real-valued quaternions
    0007 %
    0008 % Outputs:
    0009 %
    0010 %     QC(2m,...)   array of complex-valued quaternions
    0011 %
    0012 % The real-valued quaternion [r a b c]' becomes [r+j*b  a+j*c]'
    0013
    0014 %
    0015 %      Copyright (C) Mike Brookes 2000-2018
    0016 %      Version: $Id: v_rotqr2qc.m 10865 2018-09-21 17:22:45Z dmb $
    0017 %
    0018 %   VOICEBOX is a MATLAB toolbox for speech processing.
    0019 %   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
    0020 %
    0021 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    0022 %   This program is free software; you can redistribute it and/or modify
    0023 %   it under the terms of the GNU Lesser General Public License as published by
    0024 %   the Free Software Foundation; either version 3 of the License, or
    0025 %   (at your option) any later version.
    0026 %
    0027 %   This program is distributed in the hope that it will be useful,
    0028 %   but WITHOUT ANY WARRANTY; without even the implied warranty of
    0029 %   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    0030 %   GNU Lesser General Public License for more details.
    0031 %
    0032 %   You can obtain a copy of the GNU Lesser General Public License from
    0033 %   https://www.gnu.org/licenses/ .
    0034 %
    0035 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    0036 persistent a b
    0037 if isempty(a)
    0038     a=[1 3 2 4];
    0039     b=[1 1i];
    0040 end
    0041 s=size(qr);
    0042 qq=reshape(qr,4,[]);
    0043 s(1)=s(1)/2;
    0044 qc=reshape(b*reshape(qq(a,:),2,[]),s);
    0045 if ~nargout
    0046     v_rotqr2ro(qq(:,1)); % plot a rotated cube
    0047 end