function r=diffrows(m)
%DIFROWS Returns true if all rows in a matrix are different
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%  R=DIFFROWS(m)
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%    R - true if all rows in m are different, false otherwise
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%    m - Any matrix
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%  See also:
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%    LEXSORT
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%  04/06/1999 ; Pedro Frazão Ferreira
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r=all(any(diff(lexsort(m))'));