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These files are maintained strictly for historical reference, research, and recordkeeping purposes,
and the content has not been altered or updated since archiving.
Content on this site may not meet current digital accessibility standards.
If you require an alternative, accessible format of any information found on this site,
please contact Bruce Jones, bjones@ucsd.edu to request an accommodation.
matrix operations are non-commutative in general. oooops! OK, point taken about "who is going to educate the educator" nevertheless, i thought perhaps we can use insights about the determinants to help us design explanation aids for the child. the (+/- sign of) determinants determine the clockwise / anti-clockwise sense changes. we can draw x- and y- with 4 quadrants. put a two-row by three-column block of smiley faces, put an arrowhead to the left end of the smile (2×3) so it seems to indicate a clockwise rotation. reflect this in the y-axis, you get (-2×3) and the six smileys turn anti-clockwise (-6). reflect this in the x-axis, you get (-2×-3) and you see six smileys turn clockwise (+6). reflect this in the y-axis, you get (2×-3) and you see six smileys turn anti-clockwise (-6). Foo Keong NIE, Singapore 2009/4/29 Andy Blunden <ablunden@mira.net>: > But Foo Keong, > Are you seriously suggesting that Mike should use these observation about > the commutativity of matrix operations and their determinants to teach his > granddaughter why -x-=+? > I suspect that Mike doesn't understand it himself. > Who is to educate the educator? > Andy _______________________________________________ xmca mailing list xmca@weber.ucsd.edu http://dss.ucsd.edu/mailman/listinfo/xmca