mgrk — Mathematical Greek
mgrk (Mathematical Greek) replaces standard typographic forms of Greek glyphs with the forms commonly used in mathematical notation.
Applied to Σ (Sigma), for example, it produces the summation glyph (U+2211).
It is off by default. Math-oriented applications may activate it by default.
Example
Section titled “Example”Without mgrk
ΣΠ
With mgrk
ΣΠ
.fea source
Compiling…
Writing it in a feature file
Section titled “Writing it in a feature file”The rules are written with Lookup Type 1.
Without rules
ΣΠ
With rulesΣΠ
Compiling…