Cfrgtkky

I am writting a report and I have multiple systems of equations. I want to avoid have too big numbers (Equation 4.200 for example) and I dont want to link the numbering to the chapter or the section.

I want a personalized align enviroment that enummerates the equations as:

(A1)

(A2)

(A3)

The first time I use it and

(B1)

(B2)

(B3)

The second time I use and so on.

The normal numeration of the usual align enviroment or equation enviroment should not be afffected.

I have been trying for some hours but none of the answers seems to work :(

Thanks in advance!!

We can locally change the equation counter (restoring it at the end). This also behaves well with label and ref.

documentclass{article}

usepackage{amsmath}



newcounter{alphalign}

renewcommand{thealphalign}{Alph{alphalign}}

newcounter{alphalignsavedequation}



newenvironment{alphalign}

 {%

  setcounter{alphalignsavedequation}{value{equation}}%

  counterwithin*{equation}{alphalign}%

  stepcounter{alphalign}%

  renewcommand{theequation}{thealphalignarabic{equation}}%

  align

 }

 {endalignsetcounter{equation}{value{alphalignsavedequation}}}



begin{document}



An equation

begin{equation}

0=0

end{equation}

An alignment with alpha

begin{alphalign}

0&=0\

1&=1\

2&=2

end{alphalign}

Another equation

begin{equation}

0=0

end{equation}

Another alignment with alpha

begin{alphalign}

0&=0\

1&=1\

2&=2

end{alphalign}

Another equation

begin{equation}

0=0

end{equation}



end{document}

The following code lets the equation counter to another counter called selfalign within the newly-defined environment (group) selfalign. Since the let is scoped/temporary within the group, it reverts to the original definition afterwards. alphalph is used to ensure the selfalign counter prefix can roll over beyond Z, if needed.

documentclass{article}



usepackage{amsmath,alphalph}

newcounter{selfalignprefix}

newcounter{selfalign}[selfalignprefix]



renewcommand{theselfalignprefix}{AlphAlph{value{selfalignprefix}}}

renewcommand{theselfalign}{theselfalignprefixarabic{selfalign}}



makeatletter

newenvironment{selfalign}

  {letc@equationc@selfalign% Make equation counter point to the selfalign counter

   stepcounter{selfalignprefix}% Step the prefix counter

   renewcommand{theequation}{theselfalign}% Update equation counter representation

  align}

  {endalign}

makeatother



begin{document}



begin{align}

  f(x) \ g(x) \ h(x)

end{align}



begin{selfalign}

  f(x) \ g(x) \ h(x)

end{selfalign}



begin{align}

  f(x) \ g(x) \ h(x)

end{align}



begin{selfalign}

  f(x) \ g(x) \ h(x)

end{selfalign}



end{document}