📉 函数绘图计算器Graphing Calculator
绘制一个或多个 y = f(x) 函数（每行一个），带坐标刻度和网格，可缩放、拖动并导出 PNG。表达式由安全解析器求值，不执行代码。本地处理。Plot one or more y = f(x) functions (one per line) with axis ticks and a grid; zoom, drag to pan and export PNG. Expressions are evaluated by a safe parser, never run as code. Processed locally.
使用说明与常见问题How-to & FAQ
「函数绘图计算器」是什么？What is the Graphing Calculator tool?
绘制一个或多个 y = f(x) 函数（每行一个），带坐标刻度和网格，可缩放、拖动并导出 PNG。表达式由安全解析器求值，不执行代码。本地处理。Plot one or more y = f(x) functions (one per line) with axis ticks and a grid; zoom, drag to pan and export PNG. Expressions are evaluated by a safe parser, never run as code. Processed locally.
如何使用「函数绘图计算器」？How do I use the Graphing Calculator tool?
在「函数绘图计算器」中，按需设置「x 最小」、「x 最大」、「y 最小」、「y 最大」等选项，然后点击「绘制」、「放大 +」、「缩小 −」、「重置视图」按钮即可。In the Graphing Calculator: Set "x min", "x max", "y min", "y max", then click "Plot", "Zoom in +", "Zoom out −", "Reset view".
表达式安全吗？Is the expression safe?
安全。表达式由本页自带的解析器逐个符号检查后计算，只认识数字、x、pi、e、+ − × ÷ ^ 括号和白名单函数，不会把输入当作 JavaScript 执行；其他任何名字（如 alert、constructor）都会报“不认识”的错误。Yes. The page's own parser checks every token and only understands numbers, x, pi, e, + − × ÷ ^, brackets and a whitelist of functions; your input is never run as JavaScript. Any other name (such as alert or constructor) is rejected with an "Unknown name" error.
可以用哪些写法？What can I type?
运算：+ - * / ^（** 也可）、括号、负号；隐式乘法如 2x、3(x+1)、2pi x。函数：sin cos tan asin acos atan sinh cosh tanh sqrt cbrt abs ln log(=log10) log10 log2 exp floor ceil round min max pow。常数：pi（π）、e。多个参数用逗号分隔，如 max(x, 0)；小数点请用“.”。Operators: + - * / ^ (or **), brackets, unary minus; implicit multiplication like 2x, 3(x+1), 2pi x. Functions: sin cos tan asin acos atan sinh cosh tanh sqrt cbrt abs ln log (= log10) log10 log2 exp floor ceil round min max pow. Constants: pi (π), e. Separate arguments with commas, e.g. max(x, 0); use "." for decimals.
怎么缩放和移动？How do I zoom and pan?
在图上滚动鼠标滚轮以光标为中心缩放，按住拖动可平移；也可以用“放大 / 缩小 / 重置视图”按钮，或直接填写 x、y 范围（y 留空则自动）。Scroll on the graph to zoom around the cursor and drag to pan, or use the Zoom in / Zoom out / Reset view buttons, or type the x and y ranges (leave y empty for automatic).
tan(x) 这类函数为什么不会画出竖线？Why doesn't tan(x) draw vertical lines?
自动 y 范围会忽略最极端的 2% 取值，并在相邻两点跳变超过两倍可视高度时断开曲线，所以渐近线处不会连成竖线。The automatic y-range ignores the most extreme 2% of values, and the curve is broken where two neighbouring points jump by more than twice the visible height, so asymptotes are not joined by vertical lines.
有哪些选项可以调整？What options can I adjust?
「函数绘图计算器」的设置：「x 最小」默认 -6.28；「x 最大」默认 6.28；「y 最小」可留空；「y 最大」可留空。每次生成结果都按当前设置处理。Settings in the Graphing Calculator — "x min" default -6.28; "x max" default 6.28; "y min" optional; "y max" optional. The result always uses the current settings.
计算精度如何？How precise are the results?
「函数绘图计算器」使用 JavaScript 双精度浮点数（约 15–16 位有效数字）；极大或极小的数值可能存在精度误差。The Graphing Calculator uses double-precision floating point (about 15–16 significant digits); very large or very small values may lose precision.
「函数绘图计算器」免费吗？需要注册吗？Is the Graphing Calculator free? Do I need an account?
「函数绘图计算器」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Graphing Calculator is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.