我正在尝试将 TikZ 生成的一些图形居中。在我的示例中，我有三个大型 Tikz 图片，它们是单独的图形。我也有相同的三张图片，但这次是子图。
所有图形在文档中都不是完全居中（它们可能看起来居中，但略微向左悬垂）。此外，最后一张 Tikz 图片不正确；线条已移位，x 轴标签也已移位。
我怎样才能使所有图形和子图形居中？最后一张 Tikz 图片有什么问题？
\documentclass[11pt]{article}
\usepackage{amsmath,amssymb,amsfonts}
\usepackage{color}
\usepackage{amsthm,array}
\usepackage[center, labelfont=bf]{caption}
\usepackage[justification=centering, labelfont=bf]{subcaption}
\usepackage{lipsum}
\usepackage{tikz}
\usetikzlibrary{calc,arrows,through}
\RequirePackage{latexsym, verbatim, xspace, setspace}
\RequirePackage{tikz, pgflibraryplotmarks}
\setlength\parindent{0.0in}
\frenchspacing
\begin{document}
\title{Title}
\author{Author}
\date{Date}
\maketitle
\lipsum
\begin{figure}
\centering
% SLOPE FIELD 1
\begin{minipage}[t]{0.45\textwidth}
\centering
\begin{tikzpicture}[>=latex,scale=0.8]
% t-axis
\draw[thick,->] (-3.5,0) -- (3.5,0)
node[above] {$t$};
% x-axis
\draw[thick, ->] (0,-3.5) -- (0,3.5)
node[right] {$x$};
% segments
\foreach \t in {-3,-2,-1,0,1,2,3}{
\foreach \x in {-3,-2,-1,0,1,2,3}{
\draw[-, thick, color=blue] (\t,\x) -- ++({atan(\t/2)}:0.3);
\draw[-, thick, color=blue] (\t,\x) -- ++({180+atan(\t/2)}:0.3);
}}
\end{tikzpicture}
\caption{$\displaystyle \frac{dx}{dt} = \frac{t}{2}$}
\end{minipage}
\quad
% SLOPE FIELD 2
\begin{minipage}[t]{0.45\textwidth}
\centering
\begin{tikzpicture}[>=latex,scale=0.8]
% t-axis
\draw[thick,->] (-3.5,0) -- (3.5,0)
node[above] {$t$};
% y-axis
\draw[thick, ->] (0,-3.5) -- (0,3.5)
node[right] {$y$};
% segments
\foreach \t in {-3,-2,-1,0,1,2,3}{
\foreach \y in {-3,-2,-1,0,1,2,3}{
\draw[-, thick, color=blue] (\t,\y) -- ++({atan(1+\y)}:0.3);
\draw[-, thick, color=blue] (\t,\y) -- ++({180+atan(1+\y)}:0.3);
}}
\end{tikzpicture}
\caption{$\displaystyle \frac{dy}{dt} = y+1$}
\end{minipage}\\
\vspace{1cm}
% SLOPE FIELD 3
\begin{minipage}[t]{1.0\textwidth}
\centering
\begin{tikzpicture}[>=latex,scale=0.8]
% Draw x-axis
\draw[thick,->] (-3.5,0) -- (3.5,0)
node[above] {$x$};
% Draw y-axis
\draw[thick, ->] (0,-3.5) -- (0,3.5)
node[right] {$y$};
% Draw segments
\foreach \x in {-3,-2,-1,0,1,2,3}{
\foreach \y in {-3,-2,-1,0,1,2,3}{
\draw[-, thick, color=blue] (\x,\y) -- ++({atan(\x+\y)}:0.3);
\draw[-, thick, color=blue] (\x,\y) -- ++({180+atan(\x+\y)}:0.3);
}}
\end{tikzpicture}
\caption{$\displaystyle \frac{dy}{dx} = x+y$}
\end{minipage}
\end{figure}
\begin{figure}
% SLOPE FIELD 1
\centering
\begin{minipage}[t]{0.3\textwidth}
\centering
\begin{tikzpicture}[>=latex,scale=0.35]
% t-axis
\draw[thick,->] (-3.5,0) -- (3.5,0)
node[above] {$t$};
% x-axis
\draw[thick, ->] (0,-3.5) -- (0,3.5)
node[right] {$x$};
% segments
\foreach \t in {-3,-2,-1,0,1,2,3}{
\foreach \x in {-3,-2,-1,0,1,2,3}{
\draw[-, thick, color=blue] (\t,\x) -- ++({atan(\t/2)}:0.3);
\draw[-, thick, color=blue] (\t,\x) -- ++({180+atan(\t/2)}:0.3);
}}
\end{tikzpicture}
\subcaption{$\dfrac{dx}{dt} = \dfrac{t}{2}$}%\label{fig:1a}
\end{minipage}
\quad
% SLOPE FIELD 2
\centering
\begin{minipage}[t]{0.3\textwidth}
\centering
\begin{tikzpicture}[>=latex,scale=0.35]
% t-axis
\draw[thick,->] (-3.5,0) -- (3.5,0)
node[above] {$t$};
% y-axis
\draw[thick, ->] (0,-3.5) -- (0,3.5)
node[right] {$y$};
% segments
\foreach \t in {-3,-2,-1,0,1,2,3}{
\foreach \y in {-3,-2,-1,0,1,2,3}{
\draw[-, thick, color=blue] (\t,\y) -- ++({atan(1+\y)}:0.3);
\draw[-, thick, color=blue] (\t,\y) -- ++({180+atan(1+\y)}:0.3);
}}
\end{tikzpicture}
\subcaption{$\dfrac{dy}{dt} = y+1$}%\label{fig:1b}
\end{minipage}
\quad
% SLOPE FIELD 3
\centering
\begin{minipage}[t]{0.3\textwidth}
\centering
\begin{tikzpicture}[>=latex,scale=0.35]
% x-axis
\draw[thick,->] (-3.5,0) -- (3.5,0);
node[above] {$x$};
% y-axis
\draw[thick, ->] (0,-3.5) -- (0,3.5)
node[right] {$y$};
% segments
\foreach \x in {-3,-2,-1,0,1,2,3}{
\foreach \y in {-3,-2,-1,0,1,2,3}{
\draw[-, thick, color=blue] (\x,\y) -- ++({atan(\x+\y)}:0.3);
\draw[-, thick, color=blue] (\x,\y) -- ++({180+atan(\x+\y)}:0.3);
}}
\end{tikzpicture}
\subcaption{$\dfrac{dy}{dx} = x+y$}%\label{fig:1c}
\end{minipage}
\caption{Problem 3.}
\end{figure}
\lipsum
\end{document}
答案1
\centering你的第二组数字中有一些虚假数字。在最后的 中，删除中的tikzpicture分号。;\draw[thick,->] (-3.5,0) -- (3.5,0);