In Hebrew, mathematical expressions are usually written in the Latin script,
left to right. Some Arab colleagues told me that in many Arabic speaking
countries they are written in Arabic, right to left. This shouldn't surprise
anyone, as it was the Arabs who gave the world these expressions, a fact
that we remember in using the words Algebra and Algorithm, both derived from
This is relevant to items b and c.
> -----Original Message-----
> From: Marco.Cimarosti@icl.com [mailto:Marco.Cimarosti@icl.com]
> Sent: Tuesday, January 11, 2000 12:33 PM
> To: Unicode List
> Subject: Right-to-left mathematics
> Some Unicode character have the "mirrored" property. This means that, when
> they occur in a right-to-left context, they should be displayed with an
> alternative reversed glyph. For example, an open parenthesis
> looks like "("
> in LTR, but like ")" in RTL.
> a) This applies to all opening/closing punctuation, e.g.:
> U+0028 / U+0029 (LEFT ... / RIGHT PARENTHESIS)
> U+00AB / U+00BB (LEFT-... / RIGHT-POINTING DOUBLE ANGLE QUOTATION
> b) The same applies with some pairs of mathematical operators,
> that are the
> opposite of each other, both in shape as in meaning; e.g.:
> U+003C / U+003E (LESS-... / GREATER-THAN SIGN)
> U+2208 / U+220B (ELEMENT OF / CONTAINS AS MEMBER)
> c) But also some unpaired mathematical operators have the "mirrored"
> property, e.g.:
> U+221A (SQUARE ROOT)
> U+222B (INTEGRAL)
> I guess that, in cases (a) and (b), fonts actually just contain
> one pair of
> glyphs, and "swap" their encoding as needed by the bidi context. But, for
> case (c), ad-hoc reversed glyphs must be designed separately.
> Are the mirrored glyphs for case (c) operators actually used in
> right-to-left languages?
> What do mathematical formulas look like in Hebrew, Arabic, Urdu, Pashto,
> Thaana, etc.? Are they always RTL or is sometimes LTR used (as is the case
> for Hebrew music)?
> What is the attitude of font designers? Are you providing "reversed" maths
> glyphs for RTL scripts?
> Anyone knows examples of mathematical applications that implement
> bidi? How
> do they work?
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