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<div class="PlainText">Hi Michael,<br>
<br>
> On 26 Mar 2017, at 23:40, Michael Barr <barr@math.mcgill.ca> wrote:<br>
> <br>
> I got an email from a user that said:<br>
> <br>
> in xybarr.tex the line<br>
> <br>
> \newdir_{ (}{{ }*!/-.5em/@_{(}}%<br>
> <br>
> is missing, necessary to make certain hooked arrows with extra space<br>
> work correctly. <br>
<br>
We’d need to see an example of just what he means.<br>
<br>
<br>
> <br>
> 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.
<br>
<br>
<br>
> In fact, if I try to compile a diagram not even using his macro, it stops on a missing number error.
<br>
<br>
I don’t get that error at all.<br>
<br>
<br>
Look at the following comparison, when _{ (} is defined,<br>
and try it for yourself when not.<br>
<br>
<br>
>> \documentclass{article}<br>
>> \usepackage{matrix}{xy}<br>
>> \newdir_{ (}{{ }*!/-.5em/@_{(}}<br>
>> <br>
>> \begin{document}<br>
>> \[ <br>
>> \xymatrix{A & B\\ C\ar@{^(->}[ur] & D }\qquad<br>
>> \xymatrix{A & B\\ C\ar@{_(->}[ur] & D }\qquad<br>
>> \xymatrix{A & B\\ C\ar@{{ (}->}[ur] & D }\qquad<br>
>> \xymatrix{A & B\\ C\ar@{_{ (}->}[ur] & D }<br>
>> \]<br>
>> <br>
>> \end{document}<br>
<br>
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<div class="PlainText"><br>
<br>
<br>
> On the other hand, if I comment out his macro then<br>
> <br>
> \documentclass{article}<br>
> \usepackage[barr]{xy}<br>
> <br>
> <br>
> % \newdir_{ (}{{ }*!/-.5em/@_{(}}%<br>
> <br>
> \begin{document}<br>
> <br>
> <br>
> $$\bfig<br>
> \Square/ (->`>`>`>/[A`B`C`D;```]<br>
> \efig$$<br>
> <br>
> \end{document}<br>
> <br>
> compiles fine and produces a hooked arrow. There is a \newdir{ (}{{ }*!/-.5em/@^{(}}.
<br>
<br>
Yes, but it hooks the wrong way.<br>
<br>
<br>
> Can anyone tell me what is going on here. What does the underscore in his \newdir mean anyway?
<br>
<br>
According to §6.1 on p.16 of xyrefer.pdf <br>
the _ is a ⟨variant⟩ specifier, which can modify directionals, as is done here.<br>
<br>
So I’d say the suggestion here is a good one, as it just<br>
adds a variant version of something that you already have.<br>
<br>
<br>
> <br>
> Michael<br>
> <br>
> _______________________________________________<br>
> xy-pic mailing list<br>
> <a href="http://tug.org/mailman/listinfo/xy-pic">http://tug.org/mailman/listinfo/xy-pic</a><br>
<br>
<br>
Hope this helps<br>
<br>
Ross<br>
<br>
<br>
Dr Ross Moore<br>
Mathematics Dept | 12 Wally’s Walk, 734<br>
Macquarie University, NSW 2109, Australia<br>
T: +61 2 9850 8955 | F: +61 2 9850 8114<br>
M:+61 407 288 255 | E: ross.moore@mq.edu.au<br>
<br>
<a href="http://www.maths.mq.edu.au">http://www.maths.mq.edu.au</a><br>
<br>
<br>
<<a href="http://mq.edu.au/">http://mq.edu.au/</a>></div>
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