Take the 2-minute tour ×  I need to make something that should
look like this (sorry for such low quality of picture)  enter
image description here  So I type this but it's doesn't work
correctly:       \node (A) at (0,0) {$ \vec{\bf r} = \vec{\bf
R}(\vec{\bf r},\bf t)$};      \node (B) at (0, 20)
{$ X_1 = X_1(X_1,X_2,X_3,t) $};                   {$ x_3 =
x_3(X_1,X_2,X_3,t) $};      \draw[->] (A) -| node[near
start,below]  (B);   Here are some errors (which are related to
this code part) from .log:  line 0: Argument of
\tikz@scan@no@calculator has an extra } line 0: Package tikz
Error: Giving up on this path. Did you forget a semicolon? line
277: Bad math environment delimiter. {$ line 277: Missing $
inserted {$ X_ line 277: Missing \cr inserted {$ X_1 =
X_1(X_1,X_2,X_3,t) $} line 0: Misplaced \crcr line 0: Missing
\endgroup inserted line 283: Missing $ inserted \] line 283:
Missing } inserted \] line 284: Package tikz Error: Giving up on
this path. Did you forget a semicolon? $} line 285: Mi