我的MWE如下：
\usepackage{tikz,pgfplots,tikz-3dplot}
\pgfplotsset{compat=newest}
\usetikzlibrary{calc,quotes,angles,intersections,decorations.pathreplacing,decorations.markings,math,shapes.geometric,shapes.misc,positioning,hobby,bending,shadings,fit,arrows,shapes.arrows,fadings,patterns,patterns.meta}
\usepgfplotslibrary{polar,colorbrewer,fillbetween,groupplots}
\begin{document}
\begin{tikzpicture}[
declare function={
f(\x)=pow(\x,2)+2;
g(\x)=pow(\x,4)-2*pow(\x,2)+1;
}]
\begin{axis}[
axis lines*=middle, axis line style={-stealth'}, major tick length=2pt,
every axis x label/.style={at={(ticklabel* cs:1)},anchor=west,}, xlabel=$x$,
every axis y label/.style={at={(ticklabel* cs:1)},anchor=south,}, ylabel={$y$},
enlargelimits=upper, % ticks=none,
ymin=-0.5, xmin=-2.3,
]
\addplot[red,smooth,domain=-2:2,line width=1,name path=curve_f] {f(\x)};
\addplot[blue,smooth,domain=-1.85:1.85,line width=1,name path=curve_g] {g(\x)};
\path[domain=-1.85:0,name path=f(x)_1] plot (\x,{f(\x)});
\path[domain=-2:0,name path=g(x)_1] plot (\x,{g(\x)});
\path[name intersections={of=f(x)_1 and g(x)_1,by=A}];
\node[circle,fill=green,minimum size=6pt,inner sep=0pt] at (A){};
\draw[gray,dashed] (A) -- ($(0,0)!(A)!(1,0)$);
\end{axis}
\end{tikzpicture}
\end{document}
我想要填充用绿色标记的交叉点 A 下方和用蓝色标记的曲线上的颜色，如下图所示：
答案1
您应该检查是否只加载了真正需要的库和包：pgfplots已经加载的tikz、您不使用的tikz-3dplot以及您加载的大多数库。
以下内容大致取自PGFlots 手册：
\documentclass[border=10pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\usetikzlibrary{arrows}
\usepgfplotslibrary{fillbetween}
\begin{document}
\begin{tikzpicture}[
declare function={
f(\x)=pow(\x,2)+2;
g(\x)=pow(\x,4)-2*pow(\x,2)+1;
}]
\begin{axis}[
axis lines*=middle, axis line style={-stealth'}, major tick length=2pt,
every axis x label/.style={at={(ticklabel* cs:1)}, anchor=west},
xlabel=$x$,
every axis y label/.style={at={(ticklabel* cs:1)}, anchor=south},
ylabel={$y$},
enlargelimits=upper, % ticks=none,
ymin=-0.5, xmin=-2.3,
]
\addplot[red, smooth, domain=-2:2, line width=1, name path=curve_f] {f(\x)};
\addplot[blue, smooth, domain=-1.85:1.85, line width=1, name path=curve_g] {g(\x)};
\path[domain=-1.85:0, name path=f(x)_1] plot (\x, {f(\x)});
\path[domain=-2:0, name path=g(x)_1] plot (\x, {g(\x)});
\path[name intersections={of=f(x)_1 and g(x)_1, by=A}];
\node[circle, fill=green, minimum size=6pt, inner sep=0pt] at (A) {};
\draw[gray, dashed] (A) -- (A |- 0,0);
\path[name path=base]
(\pgfkeysvalueof{/pgfplots/xmin},0) --
(\pgfkeysvalueof{/pgfplots/xmax},0);
\addplot[red] fill between [of=g(x)_1 and base, soft clip={(A) rectangle (-1,0)}];
\end{axis}
\end{tikzpicture}
\end{document}
或者如果您也想使用它intersections来识别蓝色曲线的左最小值：
\documentclass[border=10pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\usetikzlibrary{arrows}
\usepgfplotslibrary{fillbetween}
\begin{document}
\begin{tikzpicture}[
declare function={
f(\x)=pow(\x,2)+2;
g(\x)=pow(\x,4)-2*pow(\x,2)+1;
}]
\begin{axis}[
axis lines*=middle, axis line style={-stealth'}, major tick length=2pt,
every axis x label/.style={at={(ticklabel* cs:1)}, anchor=west},
xlabel=$x$,
every axis y label/.style={at={(ticklabel* cs:1)}, anchor=south},
ylabel={$y$},
enlargelimits=upper, % ticks=none,
ymin=-0.5, xmin=-2.3,
]
\addplot[red, smooth, domain=-2:2, line width=1, name path=curve_f] {f(\x)};
\addplot[blue, smooth, domain=-1.85:1.85, line width=1, name path=curve_g] {g(\x)};
\path[domain=-1.85:0, name path=f(x)_1] plot (\x, {f(\x)});
\path[domain=-2:0, name path=g(x)_1] plot (\x, {g(\x)});
\path[name intersections={of=f(x)_1 and g(x)_1, by=A}];
\node[circle, fill=green, minimum size=6pt, inner sep=0pt] at (A) {};
\draw[gray, dashed] (A) -- (A |- 0,0);
\path[name path=base]
(\pgfkeysvalueof{/pgfplots/xmin},0) --
(\pgfkeysvalueof{/pgfplots/xmax},0);
\path[name intersections={of=base and g(x)_1, by=B}];
\node[circle, fill=green, minimum size=6pt, inner sep=0pt] at (B) {};
\addplot[red] fill between [of=g(x)_1 and base, soft clip={(A) rectangle (B)}];
\end{axis}
\end{tikzpicture}
\end{document}
