I have read the related question(Difference between align and alignat environments), which had detailed answer but still don't know what the meaning of the \alignat
's argument. It is said in http://people.cs.uchicago.edu/~ivan/math/amsldoc.pdf that
This environment takes one argument, the number of “equation columns”: count the maximum number of
&
s in any row, add 1 and and divide by 2.
What is the meaning of adding one in &
number and divide by two? I presumed the argument is given by the user, not automatically generated by the system?
\begin{alignat}{3}
means you want three pairs of “right-left columns”. Hence you need five&
as separator between the total six columns. – egreg Jan 18 '18 at 18:31&
, and thaat inside each column the alignment point has to be specified by another&
. For n columns, this makes 2n – 1&
. – Bernard Jan 18 '18 at 19:27