From barr at math.mcgill.ca  Sun Mar 26 14:40:26 2017
From: barr at math.mcgill.ca (Michael Barr)
Date: Sun, 26 Mar 2017 08:40:26 -0400 (EDT)
Subject: [Xy-pic] \newdir
Message-ID: <1758963272.4144464.1490532026644.JavaMail.zimbra@math.mcgill.ca>

I got an email from a user that said:

in xybarr.tex the line

\newdir_{ (}{{ }*!/-.5em/@_{(}}%

is missing, necessary to make certain hooked arrows with extra space
work correctly. 

He called it a bug.  Now I never claimed to put every arrow type into diagxy (= xybarr, not my name for it) and I admit to understanding \newdir much less well than I would like to, but I cannot get his macro to work.  In fact, if I try to compile a diagram not even using his macro, it stops on a missing number error.  On the other hand, if I comment out his macro then

\documentclass{article}
 \usepackage[barr]{xy}


  % \newdir_{ (}{{ }*!/-.5em/@_{(}}%

\begin{document}


 $$\bfig
\Square/ (->`>`>`>/[A`B`C`D;```]
 \efig$$

\end{document}

compiles fine and produces a hooked arrow.  There is a \newdir{ (}{{ }*!/-.5em/@^{(}}.  Can anyone tell me what is going on here.  What does the underscore in his \newdir mean anyway?  

Michael


From ross.moore at mq.edu.au  Mon Mar 27 00:58:27 2017
From: ross.moore at mq.edu.au (Ross Moore)
Date: Sun, 26 Mar 2017 22:58:27 +0000
Subject: [Xy-pic] \newdir
In-Reply-To: <1758963272.4144464.1490532026644.JavaMail.zimbra@math.mcgill.ca>
References: <1758963272.4144464.1490532026644.JavaMail.zimbra@math.mcgill.ca>
Message-ID: <C3046BEB-9591-411C-8CE3-C0C94CBEF5DB@mq.edu.au>

Hi Michael,

> On 26 Mar 2017, at 23:40, Michael Barr <barr at math.mcgill.ca> wrote:
>
> I got an email from a user that said:
>
> in xybarr.tex the line
>
> \newdir_{ (}{{ }*!/-.5em/@_{(}}%
>
> is missing, necessary to make certain hooked arrows with extra space
> work correctly.

We?d need to see an example of just what he means.


>
> He called it a bug.  Now I never claimed to put every arrow type into diagxy (= xybarr, not my name for it) and I admit to understanding \newdir much less well than I would like to, but I cannot get his macro to work.


> In fact, if I try to compile a diagram not even using his macro, it stops on a missing number error.

I don?t get that error at all.


Look at the following comparison, when  _{ (}  is defined,
and try it for yourself when not.


>> \documentclass{article}
>> \usepackage{matrix}{xy}
>> \newdir_{ (}{{ }*!/-.5em/@_{(}}
>>
>> \begin{document}
>> \[
>>   \xymatrix{A & B\\ C\ar@{^(->}[ur] & D }\qquad
>>   \xymatrix{A & B\\ C\ar@{_(->}[ur] & D }\qquad
>>   \xymatrix{A & B\\ C\ar@{{ (}->}[ur] & D }\qquad
>>   \xymatrix{A & B\\ C\ar@{_{ (}->}[ur] & D }
>> \]
>>
>> \end{document}




> On the other hand, if I comment out his macro then
>
> \documentclass{article}
> \usepackage[barr]{xy}
>
>
>  % \newdir_{ (}{{ }*!/-.5em/@_{(}}%
>
> \begin{document}
>
>
> $$\bfig
> \Square/ (->`>`>`>/[A`B`C`D;```]
> \efig$$
>
> \end{document}
>
> compiles fine and produces a hooked arrow.  There is a \newdir{ (}{{ }*!/-.5em/@^{(}}.

Yes, but it hooks the wrong way.


> Can anyone tell me what is going on here.  What does the underscore in his \newdir mean anyway?

According to ?6.1 on p.16 of  xyrefer.pdf
the _ is a  ?variant? specifier, which can modify directionals, as is done here.

So I?d say the suggestion here is a good one, as it just
adds a variant version of something that you already have.


>
> Michael
>
> _______________________________________________
> xy-pic mailing list
> http://tug.org/mailman/listinfo/xy-pic


Hope this helps

        Ross


Dr Ross Moore
Mathematics Dept | 12 Wally?s Walk, 734
Macquarie University, NSW 2109, Australia
T: +61 2 9850 8955  |  F: +61 2 9850 8114
M:+61 407 288 255  |  E: ross.moore at mq.edu.au

http://www.maths.mq.edu.au


 <http://mq.edu.au/>
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From ross.moore at mq.edu.au  Mon Mar 27 01:47:33 2017
From: ross.moore at mq.edu.au (Ross Moore)
Date: Sun, 26 Mar 2017 23:47:33 +0000
Subject: [Xy-pic] \newdir
In-Reply-To: <550463765.4151567.1490571552717.JavaMail.zimbra@math.mcgill.ca>
References: <1758963272.4144464.1490532026644.JavaMail.zimbra@math.mcgill.ca>
 <C3046BEB-9591-411C-8CE3-C0C94CBEF5DB@mq.edu.au>
 <550463765.4151567.1490571552717.JavaMail.zimbra@math.mcgill.ca>
Message-ID: <0CF44CF2-0A68-423A-B531-FBBBE7B25413@mq.edu.au>

Hi Michael,

On 27 Mar 2017, at 10:39, Michael Barr <barr at math.mcgill.ca<mailto:barr at math.mcgill.ca>> wrote:

Now I am really confused.  I tried the file you sent below and it didn't compile with an error that style file matrix not found.  So I changed {matrix} to [matrix] and got a message that \ar not defined.  So I changed [matrix] to [all] and it stopped with the following error message
! Xy-pic error: illegal <dir>: \dir { (} not defined.
\xyerror@ ...#2}\fi \errmessage {Xy-pic error: #1}
                                                  }
l.9   \xymatrix{A & B\\ C\ar@{{ (}->}[ur] & D }
                                               \qquad
?


Sorry,  it should start with

  \usepackage[barr,matrix]{xy}

to pick up the      \newdir{ (}{?.}    command.
Then the variant   \newdir_{ (}{?.}   can be defined also.

Think: "you cannot have a variant of something that isn?t yet defined".


I am using the 2016 version of TeXLive, if it matters.

Michael


Hope this helps.

Ross


Dr Ross Moore

Mathematics Dept | 12 Wally?s Walk, 734
Macquarie University, NSW 2109, Australia

T: +61 2 9850 8955  |  F: +61 2 9850 8114<tel:%2B61%202%209850%209695>
M:+61 407 288 255<tel:%2B61%20409%20125%20670>  |  E: ross.moore at mq.edu.au<mailto:rick.minter at mq.edu.au>

http://www.maths.mq.edu.au<http://mq.edu.au/>


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