Talk:Counting rods

Source wanted
I haven't found the negative forms of 4, 5, 9 of the Southern Song rod numerals, and I can list only their positive forms. - TAKASUGI Shinji (talk) 18:33, 18 December 2007 (UTC)

Just Integers?
How are fractions and complex numbers represented? 75.118.170.35 (talk) 01:03, 1 February 2009 (UTC)
 * I have added a short paragraph on ancient presentation of fraction with rod numerals. There was no complex number concept in antiquity--11:02, 29 June 2011 (UTC)

Possibly useful illustration from 1712


I recently uploaded this facsimile of two pages of the Katsuyo Sampo of Japanese mathematician Seki Kowa, published in 1712. It includes a tabulation of binomial coefficients in rod numerals. I am posting here in case the editors of this page want to use it. —Dominus (talk) 19:45, 21 August 2009 (UTC)

Horizontal and vertical
The meaning of horizontal and vertical form is unclear. --Apoc2400 (talk) 00:17, 21 December 2009 (UTC)

Error in Example: Rod Numerals: -6720 should have the seven hundred digit with the slash through it to represent a negative number, just as -407 does. This is true in both the Traditional and Southern Song examples. —Preceding unsigned comment added by 24.56.153.216 (talk) 13:09, 26 January 2011 (UTC)

Why use horizontal bars?
Take one of the examples, 5089.

In the second box from the left we have the numeral representing 80, three horizontal bars under a vertical. It is already in the 'tens' position, so why reiterate this? This usage also occurs in the other examples and in the photographs. — Preceding unsigned comment added by 82.32.37.89 (talk) 23:44, 29 October 2012 (UTC)

Pictures were hard to understand
I found the pictures hard to understand because they didn't seem to match the text very well. That is, as I read the text, it didn't seem that the pictures could be explained by the sections they were located in.

The "checker counting board" diagram uses negative numbers, which aren't introduced in the text until the following section, so maybe it should be moved down to that section?

The "counting rod numerals in grids in a Japanese mathematics book" image uses rotated T (connected version of "|-") for 6, and uses "T" for 11, but the text leads one to expect it to use "T" or inverted "T" for 6. The Yang Hui (Pascal's) triangle picture, also uses a rotated T (connected version of "|-") for 6. Unless I missed it, none of the examples in the text show that version, instead talking about and showing the one which looks like a T and an inverted T.

Maybe the text should describe and show examples of the variants in the pictures? I'm not sure just how many variants there are to rod numerals, or how many this page intends to describe, but I figured I'd point out that reading the page as written, I was confused for quite awhile as to why the examples didn't match what the text was describing. 2601:9:7E00:E9B:D1A9:9CCF:69CB:2E0D (talk) 09:24, 15 March 2015 (UTC)

External links modified
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History of counting rods in Japan?
What is the earliest attribution of counting rods in Japan? How did counting rods get from China to Japan? Anything about early history of counting rods in Japana would enrich the article.

Karl gregory jones (talk) 18:14, 23 November 2018 (UTC)