pgfplot：3d 函数图

Question

后我之前的问题，我想绘制一个 3d 曲面；作为一个简单的函数，我试图渲染下面的图，但没有成功。

\documentclass{standalone}
\usepackage{blindtext}
\usepackage{pgfplots}
\pgfplotsset{compat=1.9}

\begin{document}
\begin{tikzpicture}
    \directlua{
        q = function(x)
            return x-1
        end
            z = function(x,y)
            return x^2+y^2+q(x)
        end
    }
    \pgfmathdeclarefunction{z}{2}{%
        \edef\pgfmathresult{\directlua{tex.print(z(\pgfmathfloatvalueof{#1},\pgfmathfloatvalueof{#2}))}}%
    }%
    \begin{axis}
    [
    axis lines=center,
    enlargelimits,
    tick align=inside,
    domain=-1:1,
    samples=200,
    minor tick num=5,
    ]
    \addplot3 [surf] {z(x,y)};
    \end{axis}
\end{tikzpicture}
\end{document}

Answer 1

z为函数使用大写字母，即，Z一切正常。我还建议减少你的samples，至少直到你知道它有效为止 -samples=200在这种情况下使用比在二维情况下占用更多的内存！

以下是输出samples=30

% arara: lualatex
\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.9}

\begin{document}
\begin{tikzpicture}
    \directlua{
        q = function(x)
            return x-1
        end
            Z = function(x,y)
            return x^2+y^2+q(x)
        end
    }
    \pgfmathdeclarefunction{Z}{2}{%
        \edef\pgfmathresult{\directlua{tex.print(Z(\pgfmathfloatvalueof{#1},\pgfmathfloatvalueof{#2}))}}%
    }%
    \begin{axis}
    [
    axis lines=center,
    enlargelimits,
    tick align=inside,
    domain=-1:1,
    samples=30,
    minor tick num=5,
    ]
    \addplot3 [surf] {Z(x,y)};
    \end{axis}
\end{tikzpicture}
\end{document}

Answer 2

这是一个不依赖于的版本lualatex。您必须查看实际函数是否与您上一个问题中遇到的相同麻烦。

% !TeX program=pdflatex
\documentclass{standalone}
\usepackage{blindtext}
\usepackage{pgfplots}
\pgfplotsset{compat=1.9}

\begin{document}
\begin{tikzpicture}[
        declare function = {
            q(\x) = \x - 1;
            Z(\x,\y) = \x^2 + \y^2 + q(\x);
        }
    ]
    \begin{axis}
    [
    axis lines=center,
    enlargelimits,
    tick align=inside,
    domain=-1:1,
    samples=20, % this was 200, but I changed it to 20 because of my slow PC
    minor tick num=5,
    ]
    \addplot3 [surf] {Z(x,y)};
    \end{axis}
\end{tikzpicture}
\end{document}