数学符号

1. 基础运算符号

符号 含义 示例
\(+\) 加法 (Addition) \(2 + 3 = 5\)
\(-\) 减法 (Subtraction) \(7 - 4 = 3\)
\(\times\) 乘法 (Multiplication) \(2 \times 3 = 6\)
\(\div\) 除法 (Division) \(6 \div 2 = 3\)
\(\%\) 百分比 (Percentage) \(25\% \text{ of } 80 = 20\)

2. 比较符号

符号 含义 示例
\(=\) 等于 (Equal to) \(5 = 5\)
\(\neq\) 不等于 (Not equal to) \(4 \neq 5\)
\(<\) 小于 (Less than) \(3 < 5\)
\(>\) 大于 (Greater than) \(7 > 5\)
\(\leq\) 小于或等于 (Less than or equal to) \(3 \leq 3\)
\(\geq\) 大于或等于 (Greater than or equal to) \(5 \geq 5\)
\(\approx\) 约等于 (Approximately equal to) \(\pi \approx 3.14\)
\(\equiv\) 恒等于 (Identical to) \(x \equiv x\)
\(\sim\) 相似于 (Similar to) \(\triangle ABC \sim \triangle DEF\)
\(\propto\) 正比于 (Proportional to) \(y \propto x\)

3. 集合论符号

符号 含义 示例
\(\in\) 属于 (Element of) \(2 \in \mathbb{Z}\)
\(\notin\) 不属于 (Not an element of) \(\pi \notin \mathbb{Q}\)
\(\ni\) 包含 (Contains as an element) \(\mathbb{R} \ni \pi\)
\(\subset\) 真子集 (Proper subset) \(\{1,2\} \subset \{1,2,3\}\)
\(\subseteq\) 子集 (Subset) \(\{1,2\} \subseteq \{1,2,3\}\)
\(\supset\) 真超集 (Proper superset) \(\{1,2,3\} \supset \{1,2\}\)
\(\supseteq\) 超集 (Superset) \(\{1,2,3\} \supseteq \{1,2\}\)
\(\cup\) 并集 (Union) \(A \cup B\)
\(\cap\) 交集 (Intersection) \(A \cap B\)
\(\setminus\) 差集 (Set difference) \(A \setminus B\)
\(\emptyset\) 空集 (Empty set) \(\{x \in \mathbb{N} : x < 0\} = \emptyset\)

4. 逻辑符号

符号 含义 示例
\(\wedge\) 与 (And) \(p \wedge q\)
\(\vee\) 或 (Or) \(p \vee q\)
\(\neg\) 非 (Not) \(\neg p\)
\(\Rightarrow\) 蕴含 (Implies) \(p \Rightarrow q\)
\(\Leftrightarrow\) 当且仅当 (If and only if) \(p \Leftrightarrow q\)
\(\forall\) 任意 (For all) \(\forall x \in \mathbb{R}\)
\(\exists\) 存在 (There exists) \(\exists x \in \mathbb{R}\)
\(\therefore\) 所以 (Therefore) \(A=B, B=C, \therefore A=C\)
\(\because\) 因为 (Because) \(\because A=B \text{ and } B=C, \therefore A=C\)

5. 几何符号

符号 含义 示例
\(\angle\) 角 (Angle) \(\angle ABC\)
\(\perp\) 垂直 (Perpendicular) \(l_1 \perp l_2\)
\(\parallel\) 平行 (Parallel) \(l_1 \parallel l_2\)
\(\cong\) 全等 (Congruent) \(\triangle ABC \cong \triangle DEF\)
\(\sim\) 相似 (Similar) \(\triangle ABC \sim \triangle DEF\)
\(\triangle\) 三角形 (Triangle) \(\triangle ABC\)
\(\square\) 正方形 (Square) \(\square ABCD\)
\(\circ\) 度 (Degree) \(90^\circ\)
\(\pi\) 圆周率 (Pi) \(\pi r^2\)

6. 微积分符号

符号 含义 示例
\(\int\) 积分 (Integral) \(\int_a^b f(x) dx\)
\(\oint\) 环路积分 (Contour integral) \(\oint_C f(z) dz\)
\(\partial\) 偏导数 (Partial derivative) \(\frac{\partial f}{\partial x}\)
\(\nabla\) 梯度 (Gradient) \(\nabla f\)
\(\lim\) 极限 (Limit) \(\lim_{x \to \infty} f(x)\)
\(\sum\) 求和 (Summation) \(\sum_{i=1}^n i\)
\(\prod\) 求积 (Product) \(\prod_{i=1}^n i\)
\(\frac{d}{dx}\) 导数 (Derivative) \(\frac{d}{dx} f(x)\)
\(\iint\) 二重积分 (Double integral) \(\iint_D f(x, y) dx dy\)

7. 代数符号

符号 含义 示例
\(\sqrt{}\) 平方根 (Square root) \(\sqrt{4} = 2\)
\(\sqrt[n]{}\) n次方根 (nth root) \(\sqrt[3]{8} = 2\)
\(\|x\|\) 绝对值 (Absolute value) \(\|-5\| = 5\)
\(n!\) 阶乘 (Factorial) \(5! = 120\)
\(\binom{n}{k}\) 二项式系数 (Binomial coefficient) \(\binom{5}{2} = 10\)
\(\oplus\) 异或 (Exclusive or) \(1 \oplus 1 = 0\)
\(\otimes\) 克罗内克积 (Kronecker product) \(A \otimes B\)

8. 数论符号

符号 含义 示例
\(\mid\) 整除 (Divides) \(3 \mid 9\)
\(\nmid\) 不整除 (Does not divide) \(3 \nmid 10\)
\(\pmod{}\) 取模运算 (Modulo operation) \(7 \pmod{3} \equiv 1\)
\(\gcd\) 最大公约数 (Greatest common divisor) \(\gcd(12,18) = 6\)
\(\text{lcm}\) 最小公倍数 (Least common multiple) \(\text{lcm}(4,6) = 12\)
\(\infty\) 无穷大 (Infinity) \(\lim_{x \to 0} \frac{1}{x} = \infty\)

9. 矩阵与线性代数符号

符号 含义 示例
\(\det\) 行列式 (Determinant) \(\det(A)\)
\(\text{tr}\) 矩阵的迹 (Trace of a matrix) \(\text{tr}(A)\)
\(A^T\) 矩阵转置 (Matrix transpose) \((A^T)_{ij} = A_{ji}\)
\(A^{-1}\) 矩阵逆 (Matrix inverse) \(AA^{-1} = I\)
\(\ker\) 核 (Kernel) \(\ker(T)\)
\(\text{Im}\) 像 (Image) \(\text{Im}(T)\)
\(\text{rank}\) 秩 (Rank) \(\text{rank}(A)\)
\(\dim\) 维数 (Dimension) \(\dim(V)\)
\(\text{span}\) 张成 (Span) \(\text{span}\{v_1, v_2, \ldots, v_n\}\)
\(\cdot\) 点积 (Dot product) \(\mathbf{a} \cdot \mathbf{b} = a_1 b_1 + a_2 b_2 + a_3 b_3\)
\(\times\) 叉积 (Cross product) \(\mathbf{a} \times \mathbf{b} = (a_2 b_3 - a_3 b_2, a_3 b_1 - a_1 b_3, a_1 b_2 - a_2 b_1)\)
\(\otimes\) 克罗内克积 (Kronecker product) \(A \otimes B\)
\(\mathbf{0}\) 零向量 (Zero vector) \(\mathbf{0} = (0, 0, \ldots, 0)\)

10. 复数符号

符号 含义 示例
\(i\) 虚数单位 (Imaginary unit) \(i^2 = -1\)
\(z^*\) 复共轭 (Complex conjugate) \((a+bi)^* = a-bi\)
\(\|z\|\) 模 (Modulus) \(\|3+4i\| = 5\)
\(\arg(z)\) 辐角 (Argument) \(\arg(1+i) = \frac{\pi}{4}\)

11. 统计符号

符号 含义 示例
\(\mu\) 总体均值 (Population mean) \(\mu = \frac{1}{N}\sum_{i=1}^N x_i\)
\(\sigma\) 标准差 (Standard deviation) \(\sigma = \sqrt{\frac{1}{N}\sum_{i=1}^N (x_i - \mu)^2}\)
\(\sigma^2\) 方差 (Variance) \(\sigma^2 = \frac{1}{N}\sum_{i=1}^N (x_i - \mu)^2\)
\(\rho\) 相关系数 (Correlation coefficient) \(-1 \leq \rho \leq 1\)
\(\chi^2\) 卡方 (Chi-squared) \(\chi^2 = \sum \frac{(O-E)^2}{E}\)

12. 特殊常数

符号 含义 示例
\(e\) 欧拉数 (Euler's number) \(\lim_{n \to \infty} \left(1 + \frac{1}{n}\right)^n = e\)
\(\pi\) 圆周率 (Pi) \(\pi \approx 3.14159\)
\(i\) 虚数单位 (Imaginary unit) \(i^2 = -1\)
\(\gamma\) 欧拉-马斯克若尼常数 (Euler-Mascheroni constant) \(\gamma \approx 0.57721\)
\(\phi\) 黄金比例 (Golden ratio) \(\phi = \frac{1 + \sqrt{5}}{2} \approx 1.618\)
\(\zeta(3)\) 阿佩里常数 (Apéry's constant) \(\zeta(3) = \sum_{n=1}^{\infty} \frac{1}{n^3} \approx 1.20206\)
\(\ln(2)\) 2的自然对数 (Natural logarithm of 2) \(\ln(2) \approx 0.69315\)

13. 其他符号

符号 含义 示例
\(\nabla\) 梯度、散度或旋度 (Gradient, divergence, or curl) \(\nabla f\)
\(\Box\) 证明完毕 (End of proof) \(\therefore x = 2 \quad \Box\)
\(\sim\) 服从分布 (Distributed as) \(X \sim N(\mu, \sigma^2)\)
\(\asymp\) 渐近等价 (Asymptotically equivalent) \(f(x) \asymp g(x)\)
\(\ll\) 远小于 (Much less than) \(1 \ll 1000\)
\(\gg\) 远大于 (Much greater than) \(1000 \gg 1\)
\(\to\) 趋向于 (Tends to) \(x \to \infty\)
\(\mapsto\) 映射到 (Maps to) \(f: x \mapsto x^2\)

希腊字母表

小写符号 大写符号 读音 含义 示例
\(\alpha\) \(A\) 阿尔法 角度、系数 \(\alpha = 45^\circ\)
\(\beta\) \(B\) 贝塔 角度、系数 \(\beta = 0.5\)
\(\gamma\) \(\Gamma\) 伽马 伽马函数 \(\Gamma(x)\)
\(\delta\) \(\Delta\) 德尔塔 德尔塔函数、变化量 \(\Delta x = x_2 - x_1\)
\(\epsilon\) \(E\) 艾普西龙 微小量、介电常数 \(\epsilon > 0\)
\(\zeta\) \(Z\) 泽塔 泽塔函数 \(\zeta(s)\)
\(\eta\) \(H\) 伊塔 效率、粘度 \(\eta = 0.8\)
\(\theta\) \(\Theta\) 西塔 角度 \(\theta = 30^\circ\)
\(\iota\) \(\iota\) 约塔 微小量、索引 \(\iota_n\)
\(\kappa\) \(K\) 卡帕 曲率 \(\kappa = \frac{1}{R}\)
\(\lambda\) \(\Lambda\) 兰姆达 特征值、波长 \(\lambda = 500 \, \text{nm}\)
\(\mu\) \(M\) 均值、磁矩 \(\mu = 10\)
\(\nu\) \(N\) 频率 \(\nu = 60 \, \text{Hz}\)
\(\xi\) \(\Xi\) 克西 随机变量 \(\xi \sim N(0, 1)\)
\(o\) \(O\) 奥密克戎 奥密克戎 \(o(n)\)
\(\pi\) \(\Pi\) 圆周率、乘积 \(\pi \approx 3.14\)
\(\rho\) \(P\) 密度、电阻率 \(\rho = 1000 \, \text{kg/m}^3\)
\(\sigma\) \(\Sigma\) 西格玛 标准差、求和 \(\sigma = 2\)
\(\tau\) \(T\) 陶、力矩 \(\tau = 5 \, \text{Nm}\)
\(\upsilon\) \(\Upsilon\) 宇普西龙 宇普西龙 \(\Upsilon(x)\)
\(\phi\) \(\Phi\) 斐、电势 \(\phi = 10 \, \text{V}\)
\(\chi\) \(X\) 卡、卡方 \(\chi^2\)
\(\psi\) \(\Psi\) 普西 普西、波函数 \(\Psi(x, t)\)
\(\omega\) \(\Omega\) 欧米伽 欧米伽、角频率 \(\omega = 2\pi f\)