- From: David Farmer <farmer@aimath.org>
- Date: Mon, 18 Oct 2021 09:34:42 -0400 (EDT)
- To: www-math@w3.org

A previous thread cast expressions like x' as multi-character variables. I think that was the wrong way to think about it. There can be multi-character variables, but a separate and possibly more common situation is "decorated" characters. Examples, and the way I would pronounce them, are: x prime x double prime x hat x bar x tilde x check x dot x double dot x star Note that some of those have the decoration above the character, and others have the decoration above and to the right (northeast) of the character. I would be happy to hear of examples where one pronounces the decoration first and the variable second. Suppose J_0 is the 0th order Bessel function of the first kind. Is the subscript a decoration? It looks like one to me. And I pronounce it as "J zero" not "J sub zero". An intent like intent=decoration($1, $2) or intent=decoration($2, $1) indicating on the order of pronunciation, could tell AT how to say the decorated character. That intent also conveys the idea that the decorated character is one mathematical object. I say "decorated character" and not "decorated variable" because the decoration might be on a function and not on a variable. The derivative f', and Fourier transform \hat{f}, are common examples of functions with decorations. A flaw is that we have not conveyed the meaning, only the pronunciation. What if there were an (optional?) 3rd argument to the decoration intent? For example: decoration(f, hat, fourier-transform) decoration(f, prime, derivative) decoration(x, dot, time-derivative) decoration(x, bar, mean) decoration(J, 0, bessel) decoration(a, n, index) The last one would appear in sum a_n x^n because the "n" is an index (of summation), and I would pronounce the "sub" in that case. If x' is just a new variable and the prime has no meaning, that could be a case to omit the 3rd argument to decoration. All this assumes AT actually needs help pronouncing decorated characters correctly. Regards, David

Received on Monday, 18 October 2021 13:34:56 UTC