Maths glyphs in a non-maths font?

John Savard said:

Mathematics... in De Vinne??!! For some reason, that seems... strange to me.

That goes for sure! That’s why I asked if I should leave them out if not for the basic arithmetical operators.

Andreas Stötzner said:

Claudio, the idea of making summation and product a bit lighter is an interesting one. Have you considered to also give the radix a similar contrast (and perhaps a descending stretch)?

I would try out to give the horizontal part of your Delta a little more thickness.

For some reason I see the Radix as in line with basic operators, but despite being very grateful for your help, I might even decide to leave Product and Summation out altogether.
I drew the Delta, Pi and Sigma just to figure out how to treat their math counterparts: as of now I have no intention to extend De Vinne beyond its original Latin character set.

Also, please note that I have used numerators ('num') and not superscipt numerals which I have to design yet: these are old style as the original De Vinne fractions used them this way. It was just to see the effect.

Cristobal Henestrosa said:I draw product and summation with the bottom part below the baseline (but not as much as a true descender), but frankly I am not sure if this is a good choice and why.

Cristobal, the reason for which they almost always extend to the descender value is that in general they are centered with the x-height, and looking at mathematical expressions it seems they need to be large to stand out. That’s why I think they are not so useful in De Vinne, but I might include them for full "Opentype Standard" and "MacOS Roman" (et al.) encodings coverage.