On Fri, 11 Apr 2014, Sanjoy Mahajan wrote:
I cannot say whether the wrong placement is due to the wrong font metrics or the wrong mapping (mathop vs mathord) by ConTeXt.
I tried '\triangle T' (often used as the Laplacian operator, instead of writing it out as \nabla^2). That one comes out fine, even though \triangledown does not. But they seem to have similar kinds of defintions/mappings:
From luatex-math.tex :
\def\triangle {\Umathchar "0"0"0025B3 } \def\triangledown {\Umathchar "2"0"0025BD }
So it must be a wrong font metric?
AFAIU, ConTeXt does not use luatex-math.tex. The mappings are defined in char-def.lua. triangle is defined as a mathord (like nabla) while bigtriangleup is a mathop (like triangledown). Aditya