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I hope to draw the following diagram

enter image description here

Thanks a lot for your help.

marked as duplicate by Henri Menke, Masroor, Mensch, Stefan Pinnow, Andrew Swann Jan 11 at 7:40

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    If you look at the tikz-cd manual you will find it straightforward to draw this. – user121799 Jan 10 at 18:43
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    Can you please edit the title of your question to reflect what your question is about? In it's current state, it will help no future user who might have the same problem simply because nobody will be able to search for it. – user36296 Jan 10 at 19:57
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    @Schüler I have no idea what your diagram shows, so I'm not a good source of title suggestions -- but you must surly know what your question is about? – user36296 Jan 10 at 20:04
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    I guess samcarter was suggesting to make the title more relevant. For example "How do I draw commutative diagrams" or even better if this is a special kind of diagram with a name: "How do I draw Hallmackenreuther diagrams". In its current form the title may be correct, but not really helpful for other people with a similar problem. Of course you could also include a more detailed description in the question body. – moewe Jan 10 at 21:28
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    Everybody is forgetting the tilde in the answers below... lol of course it does not matter... :-) – Sigur Jan 10 at 21:33

The purpose of this site is to help you when you got stuck trying something, not to convert screen shots into LaTeX code.

\mathcal{H} \arrow[d,"W_A" swap] \arrow[r,"T"]& \mathcal{H} \arrow[d,"W_A"] \\
\mathbf{R}(A^{1/2}) \arrow[r,"T" swap] & \mathbf{R}(A^{1/2})\\

enter image description here

  • when I compile it looks a little small. Can I enlarge it a bit? Thank a lot for your help. – Schüler Jan 10 at 18:54
  • @Schüler Sure, as explained e.g. in this answer you may just replace \begin{tikzcd}by e.g. \begin{tikzcd}[sep=huge]. – user121799 Jan 10 at 18:58

Similar output of the great user @marmot using an alternative xy package from this guide XY-pic.

enter image description here

\mathcal{H} \ar[d]_{W_A} \ar[r]^T
& \mathcal{H} \ar[d]^{W_A}\\
\mathbf{R}(A^{1/2}) \ar[r]^{\tilde T} & \mathbf{R}(A^{1/2})}
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    Why you started your diagram with empty col (by &)? – Sigur Jan 10 at 21:31
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    Also, mathtools is not necessary. – Sigur Jan 10 at 21:34
  • Yes, a 2x2 matrix. – Sigur Jan 10 at 21:34
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    You need only { ... & ... \\ ... & ...} – Sigur Jan 10 at 21:37
  • @Sigur I have edited all. Thank you very much. – Sebastiano Jan 10 at 21:47

Obligatory tikzcd editor answer: https://tikzcd.yichuanshen.de/

Click the screenshot to open in the editor.

enter image description here

Generated code by clicking the {} button (not an MWE):

\mathcal{H} \arrow[rr, "T"] \arrow[d, "W_A"'] &  & \mathcal{H} \arrow[d, "W_A"] \\
\mathbf{R}(A^{1/2}) \arrow[rr, "\tilde{T}"] &  & \mathbf{R}(A^{1/2})

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