hfill in equation (split, align or subequations, ...)

Question

I'd like to have something like this

\documentclass[a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[a4paper,top=3cm,bottom=3cm,left=1.5cm,right=1.5cm]{geometry}
\usepackage{mathtools}
\usepackage{stix}
\newcommand{\tonde}[1]{\bigl(#1\bigr)}
\newcommand{\Quadre}[1]{\left[#1\right]}
\newcommand{\normadue}[1]{\left|#1\right|}
\makeatletter
\newcommand{\pushright}[1]{\ifmeasuring@#1\else\omit\hfill$\displaystyle#1$\fi\ignorespaces}
\newcommand{\pushleft}[1]{\ifmeasuring@#1\else\omit$\displaystyle#1$\hfill\fi\ignorespaces}
\makeatother
\begin{document}
\Large
\section{Introduction}
\begin{equation}
\begin{split}
L\tonde{f\circ\phi}&=\int_I\normadue{\nabla\tonde{f\circ\phi}\tonde{t}}dt=\int_I\normadue{df_{\phi(t)}\Quadre{\nabla\phi\tonde{t}}}dt\&=\int_I\normadue{\nabla\phi\tonde{t}}dt=L\tonde{\phi}\qquad\qquad\qquad\qquad\qquad\qquad\qquad\square\notag
\end{split}
\end{equation}
\end{document}

But I used \qquad 7 times. Is there I way to simplify my code using a hfill (or other else) such that the \square is in the same place of the tag of the equation? I tried with this solution but I dislike the result. Could you help me? Thank you so much

You might want to explain what your end goal is without us having to compile the example. — daleif, Jun 08 '22 at 13:48
@egreg My tag is not meaningless. Its meaning is that this splitted formula is the end of the first part of a proof. — Puck, Jun 08 '22 at 14:00
Ah, Sorry! I first wrote them in Italian and the translation maybe have changed something... . Thank you for your correction — Puck, Jun 08 '22 at 14:06

score 1 · Accepted Answer · answered Jun 08 '22 at 14:10

Do you mean something like \qedhere?

\documentclass[a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[a4paper,top=3cm,bottom=3cm,left=1.5cm,right=1.5cm]{geometry}
\usepackage{mathtools}
\usepackage{amsthm}
\usepackage{stix}
%\newcommand{\tonde}[1]{\bigl(#1\bigr)}
%\newcommand{\Quadre}[1]{\left[#1\right]}
%\newcommand{\normadue}[1]{\left|#1\right|}
\DeclarePairedDelimiter{\tonde}{(}{)}
\DeclarePairedDelimiter{\Quadre}{[}{]}
\DeclarePairedDelimiter{\normadue}{|}{|}
%\makeatletter
%\newcommand{\pushright}[1]{\ifmeasuring@#1\else\omit\hfill$\displaystyle#1$\fi\ignorespaces}
%\newcommand{\pushleft}[1]{\ifmeasuring@#1\else\omit$\displaystyle#1$\hfill\fi\ignorespaces}
%\makeatother
\begin{document}
\section{Introduction}
\begin{proof}[First part of the proof]
\begin{equation}
\begin{split}
L\tonde{f\circ\phi}
  &=\int_I\normadue{\nabla\tonde{f\circ\phi}\tonde{t}},dt
   =\int_I\normadue{df_{\phi(t)}\Quadre{\nabla\phi\tonde{t}}}dt\
  &=\int_I\normadue{\nabla\phi\tonde{t}}dt=L\tonde{\phi}\qedhere
\end{split}
\end{equation}
\end{proof}
\end{document}

You get the same output with

\documentclass[a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[a4paper,top=3cm,bottom=3cm,left=1.5cm,right=1.5cm]{geometry}
\usepackage{mathtools}
\usepackage{amsthm}
\usepackage{stix}
%\newcommand{\tonde}[1]{\bigl(#1\bigr)}
%\newcommand{\Quadre}[1]{\left[#1\right]}
%\newcommand{\normadue}[1]{\left|#1\right|}
\DeclarePairedDelimiter{\tonde}{(}{)}
\DeclarePairedDelimiter{\Quadre}{[}{]}
\DeclarePairedDelimiter{\normadue}{|}{|}
%\makeatletter
%\newcommand{\pushright}[1]{\ifmeasuring@#1\else\omit\hfill$\displaystyle#1$\fi\ignorespaces}
%\newcommand{\pushleft}[1]{\ifmeasuring@#1\else\omit$\displaystyle#1$\hfill\fi\ignorespaces}
%\makeatother
\begin{document}
\section{Introduction}
\begin{align}
L\tonde{f\circ\phi}
  &=\int_I\normadue{\nabla\tonde{f\circ\phi}\tonde{t}},dt
   =\int_I\normadue{df_{\phi(t)}\Quadre{\nabla\phi\tonde{t}}}dt\
  &=\int_I\normadue{\nabla\phi\tonde{t}}dt=L\tonde{\phi}\tag{\qedsymbol}
\end{align*}
\end{document}

but I would ask myself what would be the meaning of ending a proof without ever having started it.

I fixed just the first space before “dt”. You want to fix all those you have in your document.

By the way, you can spot the differences between my version of \normadue and yours, where the delimiters are far too big.

Thank you. Unfortunately Overleaf gives me 2 errors (I copied both of your solutions), if you want I can load the Overleaf window. And about delimiters, I prefer a lot that they are a little bit bigger, it's just my style choice. — Puck, Jun 08 '22 at 14:21

hfill in equation (split, align or subequations, ...)

1 Answers1