I was taught with rows and columns. The summation notation is not intuitive: we wouldn’t write coordinates on earth that way (or RA and Dec, for that matter). I was wondering whether it came about from typesetting, as it keeps everything on the line?

]]>I used underline rather than the arrow (and double underline for a matrix) until I started to get them confused with printers’ instructions for italic and bold face espectively…

]]>I also seem to recall that we learned about vectors before matrices, which may explain it.

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