madruwb notation

Hello,

While discussing with Azzeddine Lazrek about the madruwb notation, he 
told me that there are several variants for drawing the symbol:

- The one given in the MathML 3 spec is with a lam letter: 
http://www.w3.org/TR/MathML3/image/madruwb12.png
- However, it seems that a "right angle" is also common: 
http://upload.wikimedia.org/wikipedia/en/9/95/Arabic_mathematical_factorial.PNG
- Apparently, the "right angle" can also be oriented the other 
direction. Azzedine mentioned “Florian Cajori, A History of mathematical 
notations, Vol. 2” , p. 74 (notation used in 1827).

I wonder whether the direction of the right angle depends on the 
"overall directionality" of formulas... Also, I'm not sure whether these 
right angle notations are exactly equivalent to "right bottom" and "left 
bottom". Maybe some arabic people can tell us more about these variants 
of madruwb and whether it would be interesting to add new values for the 
"notation" attribute of menclose...

Frédéric Wang

Received on Tuesday, 19 January 2010 14:22:33 UTC