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I tried to draw the following diagram in LaTeX

enter image description here

I reference the method from here:

I can successfully compile the code from above link, but when I attempted to draw more lines between A and B by modifying the number in the:

\draw[shorten <=-1cm,shorten >=-1cm,-latex] (m-4-2.south west)--(m-4-2.south east);
\draw[shorten <=-1cm,shorten >=-1cm,-latex] (m-7-2.south east)--(m-7-2.south west);

I always got the error message said:

Package pgf Error: No shape named m-5-2 is known.

Any solution for this problem? Thanks.

share|improve this question
Welcome to TeX.SX! The syntax m-4-2 means: node in row 4 and column 2; if your matrix has no nodes in that cell, you get that error. – Claudio Fiandrino May 18 '14 at 6:51
That error can also occur if you use \node inside a matrix of nodes (see e.g. tex.stackexchange.com/questions/163319/…). Is this the case? – Torbjørn T. May 18 '14 at 7:12
Thanks for the hint! – Yang Xia May 19 '14 at 0:57
up vote 3 down vote accepted

Use a simple array environment:


\def\XLR#1{\xleftrightarrow[\rule{2cm}{0pt}]{#1}}% \rule defines the width

\begin{array}{@{} c c c @{}}
A  &  & B \\
   & \XLR{\text{KE}} \\
\text{obtain }k,T^A_{\text{KE}} &  & \text{obtain }k,T^B_{\text{KE}} \\
K:= \text{PRF}(k,\text{"KE"})   &  & K:= \text{PRF}(k,\text{"KE"})   \\
K_\text{mac}:= \text{PRF}(k,\text{"MAC"})   &  & K_\text{mac}:= \text{PRF}(k,\text{"MAC"}) \\
   & \XR{r_A} \\
   & \XL{r_B} \\

enter image description here

share|improve this answer
Thanks a lot. I figured out my own way to do it :) – Yang Xia May 19 '14 at 0:56

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