Math characters problems

[thlinard]

1. Math characters should be aligned on the Math axis (same vertical axis as hyphen, en dash and em dash when old style figures are default, otherwise same vertical axis as hyphen, en dash and em dash with case feature).
2. ∑ should be as big as ∏.
3. ≤ is wrong (VF version).

Example with <>=×÷+−¬≠≤≥∏∑

[thlinard]

Good reference:
http://www.typoma.com/publ/20041002-atypi.pdf

[peppidesu]

a lot of fonts connect the plus sign to the minus sign in the '±' glyph. you might want to do some research on if doing so makes the font more readable.