Systeme – How to Write a System of Equations with Subscripts in the Coefficients

systeme

I am trying to type this system of equations:

I tried

\documentclass[12pt,a4paper]{article}
\usepackage{amsmath}
\begin{document}
    \begin{equation}
            \begin{cases}
            a_1 x+b_1 y+c_1 z=d_1, \\
            a_2 x+b_2 y+c_2 z=d_2, \\
            a_3 x+b_3 y+c_3 z=d_3.
        \end{cases}
    \end{equation}
\end{document}

With systeme package, I tried

\documentclass{article}
\usepackage{systeme}
\begin{document}
    \systeme[xyz]{
    a_1 x+b_1 y+c_1 z=d_1, 
    a_2 x+b_2 y+c_2 z=d_2, 
    a_3 x+b_3 y+c_3 z=d_3}
    \end{document}

How can I use system package to get the result?

Best Answer

You decide if it's worth the pain:

\documentclass[12pt,a4paper]{article}
\usepackage{amsmath,systeme}

\begin{document}

\begin{equation}
\syssubstitute{%
  {A}{a_1}{B}{b_1}{C}{c_1}{D}{d_1}%
  {E}{a_2}{F}{b_2}{G}{c_2}{H}{d_2}%
  {I}{a_3}{J}{b_3}{K}{c_3}{L}{d_3}%
}
\systeme[xyz]{
  Ax + By + Cz = D,
  Ex + Fy + Gz = H,
  Ix + Jy + Kz = L
}
\end{equation}

\end{document}

Alternative, with comparison:

\documentclass[12pt,a4paper]{article}
\usepackage{amsmath,systeme,array}

\begin{document}

\begin{equation}
\left\{
\renewcommand{\arraystretch}{1.2}
\setlength{\arraycolsep}{0pt}
\begin{array}{ *{3}{c >{{}}c<{{}}}c }
a_1x &+& b_1y &+& c_1z &=& d_1 \\
a_2x &+& b_2y &+& c_2z &=& d_2 \\
a_3x &+& b_3y &+& c_3z &=& d_3
\end{array}
\right.
\end{equation}

\begin{equation}
\syssubstitute{%
  {A}{a_1}{B}{b_1}{C}{c_1}{D}{d_1}%
  {E}{a_2}{F}{b_2}{G}{c_2}{H}{d_2}%
  {I}{a_3}{J}{b_3}{K}{c_3}{L}{d_3}%
}
\systeme[xyz]{
  Ax + By + Cz = D,
  Ex + Fy + Gz = H,
  Ix + Jy + Kz = L
}
\end{equation}

\end{document}

Related Solutions

[Tex/LaTex] Unable to use systeme for a system of equations with \ldots and non-numeric coefficients

The systeme package cannot work with non-numeric coefficients. But you can build your own macro to copy how systeme works.

\documentclass{article}
\usepackage{xstring}
\def\typesystem#1{%
    \begingroup\expandarg
    \baselineskip=1.5\baselineskip% 1.5 to enlarge vertical space between lines
    \StrSubstitute{\noexpand#1}+{&+&}[\tempsystem]%
    \StrSubstitute\tempsystem={&=&}[\tempsystem]%
    \StrSubstitute\tempsystem,{\noexpand\cr}[\tempsystem]%
    $\vcenter{\halign{&$\hfil\strut##$&${}##{}$\cr\tempsystem\crcr}}$%
    \endgroup
}
\begin{document}
my system : \typesystem{
a_{11} x_1 + a_{12} x_2 + \ldots + a_{1m} x_m = b_1,
a_{21} x_1 + a_{22} x_2 + \ldots + a_{2m} x_m = b_2,
\vdots\hfil&&           &&       &&\vdots\hfil= \vdots,
a_{n1} x_1 + a_{n2} x_2 + \ldots + a_{nm} x_m = b_m
}
\end{document}

enter image description here

[Tex/LaTex] Define the system of “n” linear equations

You can do it with systeme, but it's better with cases. A small trick ensures perfect alignment. Compare the two versions below.

\documentclass{article}
\usepackage{amsmath,mathtools,systeme}

\newcommand{\di}[2]{#1\rlap{$\scriptstyle#2$}\hphantom{n}}

\newcommand{\sysdots}{%
  \hbox{\kern-0em$\cdotp\cdotp\cdotp\cdotp\cdotp\cdotp$}%
}

\begin{document}
\[
\begin{cases}
  w_1^S(\delta)=\alpha_1w_{\di 11} + \alpha_2w_{\di 21} + \dots + \alpha_nw_{\di n1}\\
  w_2^S(\delta)=\alpha_1w_{\di 12} + \alpha_2w_{\di 22} + \dots + \alpha_nw_{\di n2}\\
  \makebox[4em]{\dotfill}\\
  w_n^S(\delta)=\alpha_1w_{\di 1n} + \alpha_2w_{\di 2n} + \dots + \alpha_nw_{\di nn}
\end{cases}
\]
\[
\syssubstitute{{w_3}{\sysdots}{w_4}{w_n}}
\systeme*{
  w_1^S(\delta)=\alpha_1w_{11} + \alpha_2w_{21} + \dots + \alpha_nw_{n1},
  w_2^S(\delta)=\alpha_1w_{12} + \alpha_2w_{22} + \dots + \alpha_nw_{n2},
  w_3,
  w_4^S(\delta)=\alpha_1w_{1n} + \alpha_2w_{2n} + \dots + \alpha_nw_{nn}
}
\]
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Unable to use systeme for a system of equations with \ldots and non-numeric coefficients

[Tex/LaTex] Define the system of “n” linear equations

Related Question