[Qtfm-announce] QTFM version 3.2
Quaternion and octonion toolbox for Matlab
Brought to you by:
n-le_bihan,
sangwine
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From: Release a. a. u. <qtf...@li...> - 2022-09-08 11:19:52
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A new release of the Quaternion Toolbox for Matlab (QTFM) has been posted on Sourceforge. -------------------------------------------------------------- Quaternion toolbox for Matlab http://qtfm.sourceforge.net/ Mailing list: qtf...@li... -------------------------------------------------------------- Copyright © 2005-2022 Stephen J. Sangwine & Nicolas Le Bihan Email: san...@us... nic...@gi... -------------------------------------------------------------- Release Notes Version 3.2 8 September 2022 The function DISPLAY has been removed from the toolbox. According to current Mathworks advice (Code Analyzer) it should not be overloaded. Removing it means that the built-in DISPLAY function is called when needed, and this then calls the overloaded quaternion or octonion DISP function as appropriate. The functions ISDIVISOR and ISNILPOTENT now work for symbolic quaternions and octonions. A bug in the pivoting code in the LU decomposition has been fixed. The candidate pivot values were wrongly taken from the diagonal below and including A(j,j) rather than from the column below and including A(j,j). Fixing this bug has resolved an issue in the test code, which manifested as failures with complex octonion matrices, but could in fact have affected any quaternion or octonion matrix. The bug came to light when working on the Clifford Toolbox for MATLAB with algebras of large dimension (because this increased the chance of a large out of tolerance error in the test code). Since the LU code is common to this toolbox and the complex octonion case was a known problem, it was possible to work out where the problem was occurring. The quaternion INV function has been modified to recover from Infs or NaNs in intermediate results, by attempting to use adjoint matrices (isomorphic real or complex matrices). If this works, a correct result will now be returned, otherwise the result will, as before, still contain Infs or Nans. A test case has been added to the test code. |