Re: Chinese rod numerals

From: Christopher Cullen (
Date: Sat Jan 10 2004 - 13:06:31 EST

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    The earliest statement on this point is that of Liu Hui 劉徽 around AD
    263, who says:


    (Jiu zhang suan shu, chapter 8 p. 175 in Guo & Liu (eds) Suan jing shi
    shu, Taibei 2001.)

    Which means that the positive rods are red and the negative black, but
    adds that when this is not the case (presumably because one does not
    have coloured rods) "one makes a difference by means of the inclined
    and straight". No further explanation is given in Liu Hui's text, but
    In later practice (as evidenced in the 13th C.) this appears to have
    meant that one set out the number as usual, but with an extra rod laid
    diagonally across the right-hand numeral of a given number. I do not
    recall having heard of any excavated sets of counting-rods showing
    signs of having been coloured, but I have not checked this.

    For completeness, perhaps one should also ask for the encoding of a set
    of "diagonally cancelled" rod numerals so that the second style for
    negative numbers could be represented.

    Christopher Cullen

    On 10 Jan 2004, at 15:25, Elliotte Rusty Harold wrote:

    > One very interesting thing I noted on the page:
    > Negative numbers were usually represented using distinguisable
    > features like color. Positive rods were usually colored red while
    > negative rods were usually colored black.
    > Wasn't there a really long thread not very long ago about whether
    > color was ever a distinguishing characteristic of two otherwise
    > identical characters?
    > --
    > Elliotte Rusty Harold
    > Effective XML (Addison-Wesley, 2003)
    > cafeaulaitA

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