Math letters in commands

Math letters in commands

[Hans Åberg]

Just found that the code below does not work as intended, because \𝐝𝐢𝐦 will be parsed as \𝐝 followed by 𝐢𝐦. Can’t tell if it ought to be changed, though one could think other cases where it might be natural. The command definition of \𝐝 works though.


\setupbodyfont[xits,10pt]

\setupmathematics[lcgreek=normal, default=normal]

\definemathcommand[𝐝𝐢𝐦][nolop]{\mfunction{𝐝𝐢𝐦}}
\definemathcommand[𝐝][nolop]{\mfunction{𝐝𝐢𝐦}}

\starttext

Note that $\𝐝𝐢𝐦 𝑉 = 𝖫$, although $\dim 𝑉 = 4$.

\stoptext


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Re: Math letters in commands

[Hans Åberg]

Found a workaround: The idea is to use \csname …\endcsname with two delimiters not likely to be used in math mode, below chosen to ‘…’.

But then there seems to be a bug in the LuaTex \letcharcode command: There must be a character between “$” and the first occurring \activecatcode letter. Possibly this also causes a bug in \startformula, as discussed before.


\setupbodyfont[xits,10pt]

\setupmathematics[lcgreek=normal, default=normal]

\def\usemathcommand#1’{\csname #1\endcsname}

\appendtoks
  \catcode`‘=\activecatcode
  \letcharcode `‘ \usemathcommand
\to \everymathematics

\definemathcommand[𝐝𝐢𝐦][nolop]{\mfunction{𝐝𝐢𝐦}}

\starttext

Note that $ ‘𝐝𝐢𝐦’ 𝑉 = 𝖫$, although $\dim 𝑉 = 4$.

And a bug: $‘𝐝𝐢𝐦’ 𝑉$.

\stoptext


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Re: Math letters in commands

[Hans Hagen]

On 9/12/2016 8:25 PM, Hans Åberg wrote:
> Found a workaround: The idea is to use \csname …\endcsname with two delimiters not likely to be used in math mode, below chosen to ‘…’.
>
> But then there seems to be a bug in the LuaTex \letcharcode command: There must be a character between “$” and the first occurring \activecatcode letter. Possibly this also causes a bug in \startformula, as discussed before.

it's not a bug .. tex looks ahead for a second $ and in the process 
expands  the next token which happens to be a letter at that point so it 
gets injected as letter (it's the way tex works)

\appendtoks
     \catcode`𝐝\lettercatcode
     \catcode`𝐢\lettercatcode
     \catcode`𝐦\lettercatcode
\to \everymathematics

\definemathcommand[𝐝𝐢𝐦][nolop]{\mfunction{𝐦𝐢𝐝}}

\starttext

Note that $ \𝐝𝐢𝐦 𝑉 = 𝖫$, although $\dim 𝑉 = 4$.

And a bug: $\𝐝𝐢𝐦 𝑉$.

\stoptext

fwiw, the current beta makes math characters also letters now

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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___________________________________________________________________________________

Re: Math letters in commands

[Hans Åberg]

> On 12 Sep 2016, at 21:45, Hans Hagen <pragma@wxs.nl> wrote:
> 
> On 9/12/2016 8:25 PM, Hans Åberg wrote:

>> But then there seems to be a bug in the LuaTex \letcharcode command: There must be a character between “$” and the first occurring \activecatcode letter. Possibly this also causes a bug in \startformula, as discussed before.
> 
> it's not a bug .. tex looks ahead for a second $ and in the process expands  the next token which happens to be a letter at that point so it gets injected as letter (it's the way tex works)

I’m not sure what you mean here: I must write $ ‘𝐝𝐢𝐦’ 𝑉$, because $‘𝐝𝐢𝐦’ 𝑉$ will not see the \catcode`‘=\activecatcode. So LuaTeX must see an ordinary letter after $ before it can see an \activecatcode character.

It does not happen with TeX using
  \catcode`\‘=\active
  \def‘#1’{\csname #1\endcsname}


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___________________________________________________________________________________

Re: Math letters in commands

[Hans Åberg]

> On 12 Sep 2016, at 21:45, Hans Hagen <pragma@wxs.nl> wrote:

> fwiw, the current beta makes math characters also letters now

I saw it. Fine!


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Re: Math letters in commands

[Hans Hagen]

On 9/12/2016 10:02 PM, Hans Åberg wrote:
>
>> On 12 Sep 2016, at 21:45, Hans Hagen <pragma@wxs.nl> wrote:
>>
>> On 9/12/2016 8:25 PM, Hans Åberg wrote:
>
>>> But then there seems to be a bug in the LuaTex \letcharcode command: There must be a character between “$” and the first occurring \activecatcode letter. Possibly this also causes a bug in \startformula, as discussed before.
>>
>> it's not a bug .. tex looks ahead for a second $ and in the process expands  the next token which happens to be a letter at that point so it gets injected as letter (it's the way tex works)
>
> I’m not sure what you mean here: I must write $ ‘𝐝𝐢𝐦’ 𝑉$, because $‘𝐝𝐢𝐦’ 𝑉$ will not see the \catcode`‘=\activecatcode. So LuaTeX must see an ordinary letter after $ before it can see an \activecatcode character.
>
> It does not happen with TeX using
>   \catcode`\‘=\active
>   \def‘#1’{\csname #1\endcsname}

sure, but when you do

\appendtoks
   \catcode`\‘=\active
   \def‘#1’{\csname #1\endcsname}
\to ...

only tokens get added to the register ... so the ‘ after the \def is not 
active (yet)

in addition when tex sees a $ it will look for a next token (in case 
it's a $ for display mode) and it sees a quote (no everymath doen then) 
which it will push back

Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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Re: Math letters in commands

[Hans Åberg]

> On 13 Sep 2016, at 07:57, Hans Hagen <pragma@wxs.nl> wrote:
> 
> On 9/12/2016 10:02 PM, Hans Åberg wrote:

>> It does not happen with TeX using
>>  \catcode`\‘=\active
>>  \def‘#1’{\csname #1\endcsname}
> 
> sure, but when you do
> 
> \appendtoks
>  \catcode`\‘=\active
>  \def‘#1’{\csname #1\endcsname}
> \to ...
> 
> only tokens get added to the register ... so the ‘ after the \def is not active (yet)
> 
> in addition when tex sees a $ it will look for a next token (in case it's a $ for display mode) and it sees a quote (no everymath doen then) which it will push back

OK. TeX does not parse the way I expected.


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Re: Math letters in commands

[Hans Åberg]

> On 13 Sep 2016, at 07:57, Hans Hagen <pragma@wxs.nl> wrote:

> sure, but when you do
> 
> \appendtoks
>  \catcode`\‘=\active
>  \def‘#1’{\csname #1\endcsname}
> \to …

FYI, this does not work for me; I must use LuaTeX \letcharcode:

\def\usemathcommand#1’{\csname #1\endcsname}

\appendtoks
  \catcode`‘=\activecatcode
  \letcharcode `‘ \usemathcommand
\to \everymathematics

Then “$” must be followed by a character other than ‘ for this command to be seen, but it works with “$$”.


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