a matrix with the lower-left half equal to the mirror image of the upper-right half; a matrix that is its own transpose.
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British Dictionary definitions for symmetric matrix
maths a square matrix that is equal to its transpose, being symmetrical about its main diagonal. A skew symmetric matrix is equal to the negation of its transpose: Compare orthogonal matrix
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012