Re: Capital K as operator like \sum

Thanks Julius, 

This would be wonderful. I am using Pagella.

This notation is not widely used, one recent source is _Continued Fractions with Applications_  by Lorentzen and Waadeland.

Matthias




> On Jun 16, 2026, at 9:47 AM, Julius Ross <[email protected]> wrote:
> 
> Agreed with Mikael: normally these "larger operators" are in the font and not just scaled using a transformation.
> 
> I am happy to (try to) make this for you as long as the font you are using has a free license.  Which math font (or fonts) did you have in mind?  Can you point to some place or places that this operator is used this way in the existing literature?   
> 
> 
> 
> 
> On Mon, Jun 15, 2026 at 11:20 AM Mikael Sundqvist <[email protected] <mailto:[email protected]>> wrote:
>> Hi,
>> 
>> On Mon, 15 Jun 2026 at 16:54, Matthias Weber <[email protected] <mailto:[email protected]>> wrote:
>> >
>> > I have tried this (copying what is done in math-lop.mkxl)
>> >
>> > \unprotect
>> > \definemathoperator [cfracts]
>> > \setupmathoperators [cfracts]  [\c!size=\v!auto]
>> > \definemathoperator [kb]       [cfracts]   [\c!left="039A]
>> > %\registermathsymbolcommand "039A \kb
>> >
>> > \protect
>> >
>> > \starttext
>> > \startformula
>> > \kb_{i=1}^\infty \frac1i \ne \sum_{i=1}^\infty \frac1i
>> > \stopformula
>> > \stoptext
>> >
>> >
>> > But the K does not scale for reasons beyond my limited understanding.
>> 
>> No scaling is used for other operators either. For the integral, for
>> example, different sizes are used (the font has different sizes) in
>> different situations. If the font has an extensible mechanism for it,
>> it can grow just as a parenthesis can. But the glyph itself is not
>> scaled.
>> 
>> So, the proper solution here is probably to fix/use a font that has
>> this operator K (I guess not unicode exists for it), also with a
>> larger variant. Letting it scale arbitrarily will probably not look
>> good.
>> 
>> /Mikael
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maillist : [email protected] / https://mailman.ntg.nl/mailman3/lists/ntg-context.ntg.nl
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