[Qtfm-announce] QTFM version 2.4

[Release a. a. u. <qtf...@li...>]

A new release of the Quaternion Toolbox for Matlab (QTFM) has
been posted on Sourceforge.

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                Quaternion toolbox for Matlab
                http://qtfm.sourceforge.net/
       Mailing list: qtf...@li...
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Copyright (c) 2005-2016 Stephen J. Sangwine & Nicolas Le Bihan
Email: san...@us...
       nic...@gi...
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                     Release Notes

Version 2.4  15 June 2016

This version of QTFM requires a minimum Matlab version of 8.6 (R2015b). The
reason for this is that a new function numArgumentsFromSubscript has been
provided in Matlab, and may be overloaded for user-defined types such as
quaternion and octonion. This permits a resolution of a long-standing
issue with the numel function, which has now been modified to return the
number of elements in an array (as would be expected). The new function
numArgumentsFromSubscript has been overloaded (inside the constructor
functions) to provide the functionality needed to support subsref and
subsasgn.

The slerp function now permits extrapolation outside the arc defined by the
first two parameters by permitting the third parameter to be less than zero
or greater than one.

A new plotting function scatter4p3 plots a full quaternion scatter plot as
four projections into 3-space (rather than 6 projections onto planes as
done by the existing scatter4 function). The labelling of the axes in
scatter4 has been changed to {W, X, Y, Z} rather than {1, I, J, K} for
better legibility (and the new function uses the same labelling).

A new file qftm_version provides a check on the latest version available
at Sourceforge (provided an Internet connection is available). The test
code calls this function, and a warning is output if a more recent version
is available.

The quaternion and octonion classes now permit the value of variables to be
seen in the variable editor (but not changed there). [The octonion case
needs some more work as the internal quaternions cannot be seen.]

Three functions called q1, q2 and q3 which returned the quaternion values
i, j and k are now obsolete. If called they return an error message. They
should be replaced in any code that uses them with qi, qj or qk respectively.
The reason is to make possible in the next release a new q1 function that
will return quaternion 1 for consistency with qi, qj and qk. (Of course
onesq with no parameters already does this, but it is not as obvious as q1.)
This release includes the corresponding octonion function o1, which returns
an octonion with value unity.

The function empty has been implemented so that it is now possible to write
quaternion.empty or quaternion.empty(0,1) to create an empty quaternion array
(with double components) and similarly for octonions.


*****************
Dr Steve Sangwine
School of Computer Science and Electronic Engineering
University of Essex
Wivenhoe Park
Colchester CO4 3SQ
United Kingdom

T: (+44) (0)1206 872401
F: (+44) (0)1206 872684

http://privatewww.essex.ac.uk/~sjs