Re: [NTG-context] mathradical defaults to "normal", should it perhaps be "default"?

7 Jun 2017

      On 6/7/2017 4:50 PM, Mikael P. Sundqvist wrote:
...
On Mon, Jun 5, 2017 at 10:24 AM, Mikael P. Sundqvist  wrote:
...
Hi,
this might be a matter of taste.
look at the output of (attached). In my opinion the first square root
is to "high", while it looks better on the second line. From
setup-en.pdf it looks like the default of \setupmathradical is set to
normal (and not default). I don't understand what normal should mean,
but I think the alternative=default looks better. (The lucida fonts
are loaded in this example, since the effect is more clear for them).
Ok, this is the story
-- radicals (roots) are rather special and have some hard coded 
properties (like always scriptscript in the degree)

-- \over (and friends) that are used in \frac (which by the way can be 
configured in many ways) has the danger of getting the wrong style as 
side effect of parsing (math list construction) and processing

-- in context we want to support color etc for noth in a consistent way 
as well as style control (important in educational math)

Normally it works out ok with the 'normal' setting but there is some 
catch here. The size of the radical symbols is determine by

-- RadicalVerticalGap             =  50
-- RadicalDisplayStyleVerticalGap = 175

(These are lucide values) and it happens that the second one if too 
large which can give a bad threshold in our case. In cambria it's

RadicalVerticalGap             = 166
RadicalDisplayStyleVerticalGap = 345

So a 1:2 ratio. If we use that for lucida it looks better, so

   lucida-opentype-math.lfg

can become:

local function FixRadicalDisplayStyleVerticalGap(value,target,original)
     local o = original.mathparameters.RadicalVerticalGap -- 50
     return 2 * o * target.parameters.factor
end

return {
     name = "lucida-opentype-math",
     version = "1.00",
     comment = "Goodies that complement lucida opentype.",
     author = "Hans Hagen",
     copyright = "ConTeXt development team",
     mathematics = {
         parameters = {
             RadicalDisplayStyleVerticalGap = 
FixRadicalDisplayStyleVerticalGap,
         },
         alternates = {
             italic       = { feature = 'ss01', value = 1, comment = 
"Mathematical Alternative Lowercase Italic" },
             arrow        = { feature = 'ss02', value = 1, comment = 
"Mathematical Alternative Smaller Arrows" },
             operator     = { feature = 'ss03', value = 1, comment = 
"Mathematical Alternative Smaller Operators" },
             calligraphic = { feature = 'ss04', value = 1, comment = 
"Mathematical Alternative Calligraphic Characters" },
             zero         = { feature = 'ss05', value = 1, comment = 
"Mathematical Alternative Zero" },
             partial      = { feature = 'ss20', value = 1, comment = 
"Mathematical Alternative Upright Partial Differential" },
         },
     },
}

It's sort of a font property: the more sizes the better and sometimes 
you're simply hit by the threshold not suiting your case.

Hans

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