Use Lua.


\def\eval#1{\ctxlua{%
    local context = context
    local _ENV = math
    context(#1)
}}

\definecolor[mycolor][r=\eval{0.5*0.7}]

\starttext

\color[mycolor]{Hello!}

\stoptext



On 18/02/19 4:37 PM, Mohammad Hossein Bateni wrote:
> Hi,
>
> When I use definecolor, (how) can I use computations in setting the value
> of a component?  Something like the following...
>
> \definecolor[mycolor][r=0.5*0.7]
>
> Thanks,
> ~MHB
>
>
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___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________