termtex

termtex

Render LaTeX math as Unicode text in the terminal.

$ termtex '\frac{-b \pm \sqrt{b^2 - 4ac}}{2a}'

-b ± √(b² - 4ac)
────────────────
       2a

Install

go install github.com/doug/termtex/cmd/termtex@latest

CLI Usage

# from argument
termtex '\sum_{i=1}^{n} i^2'

# from stdin
echo 'e^{i\pi} + 1 = 0' | termtex

# with color and italic Unicode
termtex -color -italic '\int_{0}^{\infty} e^{-x^2} dx'

# pure 7-bit ASCII output (for code comments, CI logs, terminals without good Unicode)
termtex -ascii '\frac{-b \pm \sqrt{b^2 - 4ac}}{2a}'

# markdown mode: rewrite $...$ and $$...$$ in a document and pipe into glow
cat doc.md | termtex -md | glow -

Run ./demo.sh for a full showcase.

Library Usage

import "github.com/doug/termtex"

// Simple render (Style{} is the package default)
out, err := termtex.Render(`\frac{1}{2}`, termtex.Style{})

// With style options
out, err := termtex.Render(`\frac{1}{2}`, termtex.Style{
    Color:  true,
    Italic: true,
})

// Pure ASCII output
out, err := termtex.Render(`\sqrt{\pi}`, termtex.Style{ASCII: true})

Markdown Integration

termtex can expand $...$ (inline) and $$...$$ (display) math in markdown, making it easy to integrate with terminal markdown renderers like glamour. This is the recommended path for glamour users — glamour doesn't expose a goldmark-extension hook, so preprocessing is the only way to get math into its pipeline.

// Expand math delimiters, then pass to glamour.
processed := termtex.Expand(markdownString, termtex.Style{})
out, _ := glamour.Render(processed, "auto")

See example/main.go for the full glamour pipeline.

Goldmark Extension

If you're building your own terminal renderer on top of goldmark (rather than using glamour), the termtex/goldmark subpackage provides a goldmark Extender that adds MathInline and MathBlock AST nodes plus a renderer that calls termtex.

import (
    "github.com/yuin/goldmark"
    ttgoldmark "github.com/doug/termtex/goldmark"
)

md := goldmark.New(
    goldmark.WithExtensions(ttgoldmark.NewMathExtension()),
)

Pair it with your own renderer.Renderer to control the surrounding markdown styling. (Goldmark's default renderer emits HTML, which mixes oddly with terminal-Unicode math — use this path for terminal pipelines where you control the renderer, not for HTML output. For HTML math, use KaTeX or MathJax client-side.)

Supported LaTeX

Category	Commands
Fractions	\frac{a}{b}
Superscripts / Subscripts	x^2, x_{i}, x_{i}^{2}
Square roots	\sqrt{x}, \sqrt[3]{x}
Big operators	\sum, \prod, \int, \oint with limits
Limits	\lim_{x \to 0}
Greek letters	\alpha through \omega, \Gamma through \Omega
Math fonts	\mathbb (ℕℤℚℝℂ), \mathcal (ℒℳℛ), \mathbf (𝐱), \mathfrak (𝔤), \mathsf (𝖠), \mathit
Delimiters	\left( \right), \left[ \right], \left\{ \right\}
Matrices	pmatrix, bmatrix, vmatrix, Bmatrix, Vmatrix
Accents	\hat, \bar, \vec, \dot, \ddot, \tilde, \overline, \underline
Wide accents	\widehat, \widetilde
Annotations	\overbrace{X}^{label}, \underbrace{X}_{label}
Operators	\pm, \times, \div, \cdot, \leq, \geq, \neq, \approx, \equiv
Arrows	\to, \rightarrow, \leftarrow, \Rightarrow, \Leftarrow
Sets	\in, \notin, \subset, \subseteq, \cup, \cap
Logic	\forall, \exists
Calculus	\partial, \nabla, \infty, \hbar
Brackets	\langle, \rangle, \mid
Functions	\sin, \cos, \log, \ln, \exp, \det, \max, \min, ...
Text	\text{...}
Spacing	\,, \;, \!, \quad, \qquad
Dots	\ldots, \cdots, \vdots, \ddots

Equation Gallery

100 famous equations rendered by termtex. This section is auto-generated by demo.sh.

Foundations

1. Euler's Identity e^{i\pi} + 1 = 0

 iπ
e   + 1 = 0

2. Pythagorean Theorem a^2 + b^2 = c^2

a² + b² = c²

3. Quadratic Formula \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

-b ± √(b² - 4ac)
────────────────
       2a

4. Binomial Theorem (x + y)^n = \sum_{k=0}^{n} \frac{n!}{k!(n-k)!} x^k y^{n-k}

            n      n!
(x + y)ⁿ =  ∑  ──────────xᵏyⁿ⁻ᵏ
           k=0 k!(n - k)!

5. Power Rule \frac{d}{dx} x^n = nx^{n-1}

 d
────xⁿ = nxⁿ⁻¹
 dx

6. Definition of Derivative \frac{df}{dx} = \lim_{h \to 0} \frac{f(x+h) - f(x)}{h}

 df          f(x + h) - f(x)
──── = lim   ───────────────
 dx    h→0          h

7. Fundamental Theorem of Calculus \int_{a}^{b} f(x) dx = F(b) - F(a)

b
∫ f(x)dx = F(b) - F(a)
a

8. Chain Rule \frac{dy}{dx} = \frac{dy}{du} \cdot \frac{du}{dx}

 dy     dy   du
──── = ────·────
 dx     du   dx

9. Product Rule (fg)^{\prime} = f^{\prime}g + fg^{\prime}

(fg)′ = f′g + fg′

10. Integration by Parts \int u \, dv = uv - \int v \, du

∫u dv = uv - ∫v du

Algebra and Number Theory

11. Sum of Natural Numbers \sum_{i=1}^{n} i = \frac{n(n+1)}{2}

 n      n(n + 1)
 ∑  i = ────────
i=1        2

12. Sum of Squares \sum_{i=1}^{n} i^2 = \frac{n(n+1)(2n+1)}{6}

 n       n(n + 1)(2n + 1)
 ∑  i² = ────────────────
i=1             6

13. Geometric Series \sum_{k=0}^{n} r^k = \frac{1 - r^{n+1}}{1 - r}

 n       1 - rⁿ⁺¹
 ∑  rᵏ = ────────
k=0       1 - r

14. Infinite Geometric Series \sum_{k=0}^{\infty} r^k = \frac{1}{1 - r}

 ∞         1
 ∑  rᵏ = ─────
k=0      1 - r

15. Difference of Squares a^2 - b^2 = (a + b)(a - b)

a² - b² = (a + b)(a - b)

16. Cubic Formula (Depressed) x = \sqrt[3]{-\frac{q}{2} + \sqrt{\frac{q^2}{4} + \frac{p^3}{27}}} + \sqrt[3]{-\frac{q}{2} - \sqrt{\frac{q^2}{4} + \frac{p^3}{27}}}

      ⎛   q     ⎛ q²     p³ ⎞⎞     ⎛   q     ⎛ q²     p³ ⎞⎞
x = ³√⎜- ─── + √⎜──── + ────⎟⎟ + ³√⎜- ─── - √⎜──── + ────⎟⎟
      ⎝   2     ⎝ 4      27 ⎠⎠     ⎝   2     ⎝ 4      27 ⎠⎠

17. Fraction Addition \frac{a}{b} + \frac{c}{d} = \frac{ad + bc}{bd}

 a     c    ad + bc
─── + ─── = ───────
 b     d      bd

18. Logarithm Change of Base \log_a b = \frac{\ln b}{\ln a}

         ln b
logₐ b = ────
         ln a

19. Exponential-Log Inverse e^{\ln x} = x

 ln x
e     = x

20. Euler's Totient Product \phi(n) = n \prod_{p | n} \left(1 - \frac{1}{p}\right)

            ⎛     1 ⎞
φ(n) = n ∏  ⎜1 - ───⎟
        p|n ⎝     p ⎠

Calculus and Analysis

21. Gaussian Integral \int_{0}^{\infty} e^{-x^2} dx = \frac{\sqrt{\pi}}{2}

∞          √(π)
∫ e⁻ˣ²dx = ────
0           2

22. Taylor Series f(x) = \sum_{n=0}^{\infty} \frac{f^{(n)}(a)}{n!} (x - a)^n

            (n)
        ∞  f   (a)
f(x) =  ∑  ───────(x - a)ⁿ
       n=0   n!

23. Maclaurin Series for e^x e^x = \sum_{n=0}^{\infty} \frac{x^n}{n!}

      ∞   xⁿ
eˣ =  ∑  ────
     n=0  n!

24. Basel Problem \sum_{n=1}^{\infty} \frac{1}{n^2} = \frac{\pi^2}{6}

 ∞   1      π²
 ∑  ──── = ────
n=1  n²     6

25. Leibniz Formula for Pi \frac{\pi}{4} = 1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \cdots

 π         1     1     1
─── = 1 - ─── + ─── - ─── + ⋯
 4         3     5     7

26. Cauchy-Schwarz Inequality \left(\sum a_i b_i\right)^2 \leq \left(\sum a_i^2\right)\left(\sum b_i^2\right)

(∑aᵢbᵢ)² ≤ (∑a²ᵢ)(∑b²ᵢ)

27. Mean Value Theorem f(b) - f(a) = f^{\prime}(c)(b - a)

f(b) - f(a) = f′(c)(b - a)

28. L'Hopital's Rule \lim_{x \to c} \frac{f(x)}{g(x)} = \lim_{x \to c} \frac{f^{\prime}(x)}{g^{\prime}(x)}

      f(x)         f′(x)
lim   ──── = lim   ─────
x→c   g(x)   x→c   g′(x)

29. Euler-Mascheroni Constant \gamma = \lim_{n \to \infty} \left(\sum_{k=1}^{n} \frac{1}{k} - \ln n\right)

          ⎛ n   1        ⎞
γ = lim   ⎜ ∑  ─── - ln n⎟
    n→∞   ⎝k=1  k        ⎠

30. Stirling's Approximation n! \approx \sqrt{2\pi n} \left(\frac{n}{e}\right)^n

                n
           ⎛ n ⎞
n! ≈ √(2πn)⎜───⎟
           ⎝ e ⎠

Trigonometry

31. Pythagorean Identity \sin^2 \theta + \cos^2 \theta = 1

sin² θ + cos² θ = 1

32. Sine Addition \sin(\alpha + \beta) = \sin \alpha \cos \beta + \cos \alpha \sin \beta

sin (α + β) = sin α cos β + cos α sin β

33. Cosine Addition \cos(\alpha + \beta) = \cos \alpha \cos \beta - \sin \alpha \sin \beta

cos (α + β) = cos α cos β - sin α sin β

34. Euler's Formula e^{i\theta} = \cos \theta + i \sin \theta

eⁱᶿ = cos θ + i sin θ

35. Double Angle Sine \sin 2\theta = 2 \sin \theta \cos \theta

sin 2θ = 2 sin θ cos θ

36. Double Angle Cosine \cos 2\theta = \cos^2 \theta - \sin^2 \theta

cos 2θ = cos² θ - sin² θ

37. Tangent Definition \tan \theta = \frac{\sin \theta}{\cos \theta}

        sin θ
tan θ = ─────
        cos θ

38. Law of Sines \frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C}

  a       b       c
───── = ───── = ─────
sin A   sin B   sin C

39. Law of Cosines c^2 = a^2 + b^2 - 2ab \cos C

c² = a² + b² - 2ab cos C

40. Half-Angle Formula \sin \frac{\theta}{2} = \pm \sqrt{\frac{1 - \cos \theta}{2}}

     θ      ⎛1 - cos θ⎞
sin ─── = ±√⎜─────────⎟
     2      ⎝    2    ⎠

Linear Algebra

41. 2x2 Determinant \det \begin{bmatrix} a & b \\ c & d \end{bmatrix} = ad - bc

    ⎡ a  b ⎤
det ⎣ c  d ⎦ = ad - bc

42. Kronecker Delta \delta_{ij} = \begin{cases} 1 & \text{if } i = j \\ 0 & \text{if } i \neq j \end{cases}

      ⎧ 1  if  i = j
δᵢⱼ = ⎩ 0  if  i ≠ j

43. Matrix Inverse (2x2) A^{-1} = \frac{1}{ad - bc} \begin{bmatrix} d & -b \\ -c & a \end{bmatrix}

         1   ⎡ d   -b ⎤
A⁻¹ = ───────⎣ -c  a  ⎦
      ad - bc

44. Eigenvalue Equation Av = \lambda v

Av = λv

45. Characteristic Polynomial \det(A - \lambda I) = 0

det (A - λI) = 0

46. Dot Product a \cdot b = \sum_{i=1}^{n} a_i b_i

       n
a·b =  ∑  aᵢbᵢ
      i=1

47. Cross Product a \times b = \begin{vmatrix} i & j & k \\ a_1 & a_2 & a_3 \\ b_1 & b_2 & b_3 \end{vmatrix}

        │ i   j   k  │
a × b = │ a₁  a₂  a₃ │
        │ b₁  b₂  b₃ │

48. Matrix Transpose (AB)^T = B^T A^T

(AB)ᵀ = BᵀAᵀ

49. Trace \text{tr}(A) = \sum_{i=1}^{n} a_{ii}

          n
tr (A) =  ∑  aᵢᵢ
         i=1

50. Rotation Matrix R(\theta) = \begin{bmatrix} \cos \theta & -\sin \theta \\ \sin \theta & \cos \theta \end{bmatrix}

       ⎡ cos θ  -sin θ ⎤
R(θ) = ⎣ sin θ  cos θ  ⎦

Classical Mechanics

51. Newton's Second Law F = ma

F = ma

52. E = mc^2 E = mc^2

E = mc²

53. Kinetic Energy E_k = \frac{1}{2}mv^2

      1
Eₖ = ───mv²
      2

54. Gravitational Force F = G\frac{m_1 m_2}{r^2}

     m₁m₂
F = G────
      r²

55. Gravitational Potential Energy U = -\frac{Gm_1 m_2}{r}

      Gm₁m₂
U = - ─────
        r

56. Escape Velocity v_e = \sqrt{\frac{2GM}{r}}

      ⎛2GM⎞
vₑ = √⎜───⎟
      ⎝ r ⎠

57. Simple Harmonic Motion x(t) = A\cos(\omega t + \phi)

x(t) = A cos (ωt + φ)

58. Euler-Lagrange Equation \frac{d}{dt}\frac{\partial L}{\partial v} - \frac{\partial L}{\partial q} = 0

 d   ∂L     ∂L
──────── - ──── = 0
 dt  ∂v     ∂q

59. Hamilton's Equation \frac{dq}{dt} = \frac{\partial H}{\partial p}

 dq     ∂H
──── = ────
 dt     ∂p

60. Centripetal Acceleration a = \frac{v^2}{r}

     v²
a = ────
     r

Electromagnetism

61. Gauss's Law \nabla \cdot E = \frac{\rho}{\epsilon_0}

       ρ
∇·E = ────
       ε₀

62. Gauss's Law (Magnetism) \nabla \cdot B = 0

∇·B = 0

63. Faraday's Law \nabla \times E = -\frac{\partial B}{\partial t}

           ∂B
∇ × E = - ────
           ∂t

64. Ampere's Law \nabla \times B = \mu_0 J + \mu_0 \epsilon_0 \frac{\partial E}{\partial t}

                   ∂E
∇ × B = μ₀J + μ₀ε₀────
                   ∂t

65. Coulomb's Law F = \frac{1}{4\pi\epsilon_0} \cdot \frac{q_1 q_2}{r^2}

     1   q₁q₂
F = ────·────
    4πε₀  r²

66. Lorentz Force F = q(E + v \times B)

F = q(E + v × B)

67. Ohm's Law V = IR

V = IR

68. Capacitor Energy E = \frac{1}{2}CV^2

     1
E = ───CV²
     2

69. Biot-Savart Law dB = \frac{\mu_0}{4\pi} \frac{I \, dl \times \hat{r}}{r^2}

      μ₀ I dl × r̂
dB = ────────────
      4π    r²

70. Poynting Vector S = \frac{1}{\mu_0} E \times B

     1
S = ────E × B
     μ₀

Quantum Mechanics and Relativity

71. Schrodinger Equation i\hbar\frac{\partial}{\partial t}\Psi = \hat{H}\Psi

   ∂
iℏ────Ψ = ĤΨ
   ∂t

72. Heisenberg Uncertainty \Delta x \, \Delta p \geq \frac{\hbar}{2}

         ℏ
Δx Δp ≥ ───
         2

73. de Broglie Wavelength \lambda = \frac{h}{p}

     h
λ = ───
     p

74. Planck-Einstein Relation E = h\nu

E = hν

75. Time Dilation \Delta t^{\prime} = \frac{\Delta t}{\sqrt{1 - \frac{v^2}{c^2}}}

          Δt
Δt′ = ───────────
       ⎛     v² ⎞
      √⎜1 - ────⎟
       ⎝     c² ⎠

76. Length Contraction L = L_0 \sqrt{1 - \frac{v^2}{c^2}}

       ⎛     v² ⎞
L = L₀√⎜1 - ────⎟
       ⎝     c² ⎠

77. Relativistic Energy-Momentum E^2 = (pc)^2 + (mc^2)^2

E² = (pc)² + (mc²)²

78. Schwarzschild Radius r_s = \frac{2GM}{c^2}

     2GM
rₛ = ───
     c²

79. Photoelectric Effect E_k = h\nu - \phi

Eₖ = hν - φ

80. Rydberg Formula \frac{1}{\lambda} = R\left(\frac{1}{{n_1}^2} - \frac{1}{{n_2}^2}\right)

 1     ⎛ 1     1 ⎞
─── = R⎜─── - ───⎟
 λ     ⎝n₁²   n₂²⎠

Thermodynamics

81. Ideal Gas Law PV = nRT

PV = nRT

82. Boltzmann Entropy S = k_B \ln \Omega

S = k  ln Ω
     B

83. First Law of Thermodynamics \Delta U = Q - W

ΔU = Q - W

84. Carnot Efficiency \eta = 1 - \frac{T_c}{T_h}

         T
          c
η = 1 - ────
         T
          h

85. Stefan-Boltzmann Law P = \sigma A T^4

P = σAT⁴

86. Maxwell-Boltzmann Distribution f(v) = 4\pi n \left(\frac{m}{2\pi kT}\right)^{3/2} v^2 e^{-mv^2/2kT}

                3/2      2
          ⎛ m  ⎞    2 -mv /2kT
f(v) = 4πn⎜────⎟   v e
          ⎝2πkT⎠

87. Planck's Law B(\nu) = \frac{2h\nu^3}{c^2} \cdot \frac{1}{e^{h\nu/kT} - 1}

          3
       2hν      1
B(ν) = ────·──────────
         2   hν/kT
        c   e      - 1

88. Gibbs Free Energy G = H - TS

G = H - TS

89. Clausius Inequality \oint \frac{dQ}{T} \leq 0

  dQ
∮──── ≤ 0
  T

90. Equipartition Theorem \langle E \rangle = \frac{f}{2} k_B T

       f
⟨E⟩ = ───k T
       2  B

Probability and Information

91. Bayes' Theorem P(A \mid B) = \frac{P(B \mid A) \, P(A)}{P(B)}

         P(B|A) P(A)
P(A|B) = ───────────
            P(B)

92. Normal Distribution f(x) = \frac{1}{\sigma\sqrt{2\pi}} e^{-\frac{(x - \mu)^2}{2\sigma^2}}

                (x-μ)²
              - ──────
         1       2σ²
f(x) = ──────e
       σ√(2π)

93. Expected Value E[X] = \sum_{i} x_i \, P(x_i)

E[X] = ∑ xᵢ P(xᵢ)
       i

94. Variance \text{Var}(X) = E[X^2] - (E[X])^2

Var (X) = E[X²] - (E[X])²

95. Shannon Entropy H = -\sum_{i} p_i \log_2 p_i

H = -∑ pᵢ log₂ pᵢ
     i

96. Bernoulli Trial P(k) = \frac{n!}{k!(n-k)!} p^k (1-p)^{n-k}

           n!
P(k) = ──────────pᵏ(1 - p)ⁿ⁻ᵏ
       k!(n - k)!

Famous Constants and Identities

97. Golden Ratio \phi = \frac{1 + \sqrt{5}}{2}

    1 + √(5)
φ = ────────
       2

98. Euler Product (Riemann Zeta) \zeta(s) = \sum_{n=1}^{\infty} \frac{1}{n^s} = \prod_{p} \frac{1}{1 - p^{-s}}

        ∞   1          1
ζ(s) =  ∑  ──── = ∏ ───────
       n=1  nˢ    p 1 - p⁻ˢ

99. Wallis Product \frac{\pi}{2} = \prod_{n=1}^{\infty} \frac{4n^2}{4n^2 - 1}

 π     ∞    4n²
─── =  ∏  ───────
 2    n=1 4n² - 1

100. Euler's Reflection Formula \Gamma(z)\Gamma(1-z) = \frac{\pi}{\sin(\pi z)}

                  π
Γ(z)Γ(1 - z) = ────────
               sin (πz)