![tikz中自定义常量有一个错误?](https://linux22.com/image/468297/tikz%E4%B8%AD%E8%87%AA%E5%AE%9A%E4%B9%89%E5%B8%B8%E9%87%8F%E6%9C%89%E4%B8%80%E4%B8%AA%E9%94%99%E8%AF%AF%EF%BC%9F.png)
\documentclass[notitlepage, 12pt]{amsart}
\usepackage{amsthm, amsmath, amsaddr, amssymb, graphicx, dsfont,}
\usepackage[dvipsnames]{xcolor}
\renewcommand{\baselinestretch}{1.2}
\usepackage{tikz}
\usepackage[capposition=bottom]{floatrow}
\usepackage{float}
\begin{document}
\begin{figure}[H]
\centering
\begin{tikzpicture}[xscale=8,yscale=8]
\def\epsi{0.05};
\def\aa{0.6};
\def\suppd{0};
\def\suppe{(1-\aa)/(\aa)};
\def\pd{1-\aa};
\def\yd{\pd*(\suppe-\suppd)};
\draw [<->] (0,1.1)--(0,0)--(1.1,0);
\draw (0,{(1-\aa)^2/\aa})--(1,{\yd});
\end{tikzpicture}
\end{figure}
\end{document}
代数表示 \yd 应该是 $\frac{(1-\alpha)^2}{\alpha}$,但我画的图表明情况并非如此(线不是水平的)。我想知道出了什么问题。