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尺寸过大-TikZ 数据可视化错误

tag-icon • tag-icon tikz-pgf tikz-datavisualization
尺寸过大-TikZ 数据可视化错误

这个问题是类似的。

我的任务是在一个图中绘制两个磁滞回线。我从以下函数（代表我的磁滞回线）中获取这里。

我的代码：

\documentclass{scrartcl}
\usepackage{tikz}
\usepackage[per-mode = fraction]{siunitx}
\usetikzlibrary{datavisualization.formats.functions}
\begin{document}
  \begin{tikzpicture}
    \datavisualization[
                       scientific axes = {clean, end labels},
                       all axes = {ticks and grid = {major at = 0}},
                       x axis = {label = $\frac{H}{\si{\A\per\m}}$},
                       y axis = {label = $\frac{B(H)}{\si{\tesla}}$},
                       data/format = function,
                       visualize as smooth line/.list = {left_soft, right_soft, left_hard, right_hard},
                       left_soft = {style = dashed,
                                    label in legend = {text = weichmagnetisch}
                                   },
                       right_soft = {style = dashed},
                       left_hard = {label in legend = {text = hartmagnetisch}}
                      ]
    data[set = left_soft] {
                           var x : interval [-7 : 7];
                           func y = 5 / (1 + exp(-2 * \value x - 1.5)) - 2.5;
                          }
    data[set = right_soft] {
                            var x : interval [-7 : 7];
                            func y = 5 / (1 + exp(-2 * \value x + 1.5)) - 2.5;
                           }
    data[set = left_hard] {
                           var x : interval [-7 : 7];
                           func y = 5 / (1 + exp(-.75 * \value x - 1.5)) - 2.5;
                          }
    data[set = right_hard] {
                            var x : interval [-7 : 7];
                            func y = 5 / (1 + exp(-.75 * \value x + 1.5)) - 2.5;
                           };
  \end{tikzpicture}
\end{document}

然而我得到很多

！尺寸太大 \pgfmath@iterate。...\pgfmath@xa \ifdim \pgfmath@x

错误。我该如何修复？

提前谢谢你的帮助！

答案1

对于 x=-6 和 x=-7的求值exp(-2 * \value x - 1.5)，以及exp(-2 * \value x + 1.5)对于 x=-5、-6、-7 的求值都会导致溢出。最简单的解决方法是忽略这些值，因为图形的这一部分无论如何都被其他曲线覆盖了。否则，您可以通过将 x 的错误值设置为零来分段定义函数。

enter image description here

\documentclass{scrartcl}
\usepackage{tikz}
\usepackage[per-mode = fraction]{siunitx}
\usetikzlibrary{datavisualization.formats.functions}
\begin{document}
  \begin{tikzpicture}
    \datavisualization[
                       scientific axes = {clean, end labels},
                       all axes = {ticks and grid = {major at = 0}},
                       x axis = {label = $\frac{H}{\si{\A\per\m}}$},
                       y axis = {label = $\frac{B(H)}{\si{\tesla}}$},
                       data/format = function,
                       visualize as smooth line/.list = {left_soft, right_soft, left_hard, right_hard},
                       left_soft = {style = dashed,
                                    label in legend = {text = weichmagnetisch}
                                   },
                       right_soft = {style = dashed},
                       left_hard = {label in legend = {text = hartmagnetisch}}
                      ]
    data[set = left_soft] {
                           var x : interval [-5 : 7];
                           func y = 5 / (1 + exp(-2 * \value x - 1.5)) - 2.5;
                          }
    data[set = right_soft] {
                            var x : interval [-4 : 7];
                            func y = 5 / (1 + exp(-2 * \value x + 1.5)) - 2.5;
                          }
    data[set = left_hard] {
                           var x : interval [-7 : 7];
                           func y = 5 / (1 + exp(-.75 * \value x - 1.5)) - 2.5;
                          }
    data[set = right_hard] {
                            var x : interval [-7 : 7];
                            func y = 5 / (1 + exp(-.75 * \value x + 1.5)) - 2.5;
                           }
;
  \end{tikzpicture}
\end{document}

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