formulas
Click on any formula to visit its page for more details.
Taylor & Maclaurin Series
$$f(x) = \sum_{n=0}^{\infty} \frac{f^{(n)}(a)}{n!} \cdot (x - a)^n$$
Bayes' Theorem
$$P(A|B) = \frac{P(B|A)P(A)}{P(B)}$$
Conditional Probability
$$P(E|F) = \frac{P(E \cap F)}{P(F)}$$
Gaussian/Normal Distribution
$$f(x) = \frac{1}{\sigma \sqrt{2\pi}} e^{-\frac{1}{2}\left(\frac{x-\mu}{\sigma}\right)^2}$$
Curl
$$\scriptsize \nabla \times \mathbf{F} = \begin{vmatrix} \mathbf{i} & \mathbf{j} & \mathbf{k} \\\\ \frac{\partial}{\partial x} & \frac{\partial}{\partial y} & \frac{\partial}{\partial z} \\\\ F_x & F_y & F_z \end{vmatrix}$$
Divergence
$$\nabla \cdot \mathbf{F} = \frac{\partial F_x}{\partial x} + \frac{\partial F_y}{\partial y} + \frac{\partial F_z}{\partial z}$$
Gradient
$$\nabla f = \frac{\partial f}{\partial x} \mathbf{i} + \frac{\partial f}{\partial y} \mathbf{j} + \frac{\partial f}{\partial z} \mathbf{k}$$
Matrix Multiplication
$$\scriptsize \begin{pmatrix} a & b \\ c & d \end{pmatrix} \begin{pmatrix} w & x \\ y & z \end{pmatrix} = \begin{pmatrix} aw + by & ax + bz \\ cw + dy & cx + dz \end{pmatrix}$$
Quadric Surfaces
$$\\ {x^2 \over a^2} + {y^2 \over b^2} + {z^2 \over c^2} = 1$$
Equation of a Plane
$$ax + by + cz = d$$
Equation of a Sphere
$$\small R^2 = (x-x_0)^2 + (y-y_0)^2 + (z - z_0)^2$$
Fourier + Inverse Fourier Transform
$$X(\omega) = \int_{-\infty}^{\infty}x(t)e^{-j\omega t}\,dt$$
Modulus of Resilience
$$U_r = \int_{0}^{\epsilon_Y}\sigma\mathop{d\epsilon} \approx \frac{\sigma_{YS}^2}{2E}$$
Modulus of Rigidity/Shear Modulus
$$G = \frac{\tau}{\gamma}$$
Modulus of Toughness
$$U_t = \int_{0}^{\epsilon_f}\sigma\mathop{d\epsilon}$$
Poisson's Ratio
$$\nu = - \frac{\epsilon_x}{\epsilon_z} = -\frac{\epsilon_y}{\epsilon_z}$$
Resistance in a straight conductor
$$R = \frac{\rho l}{A}$$
Thermal expansion
$$\Delta L = L_0 \alpha \Delta T$$
Arithmetic Gradients
$$\scriptsize P = A \left[\frac{(1+i)^n-1}{i(1+i)^n}\right] + G \left[\frac{(1+i)^n-in-1}{i^2(1+i)^n}\right]$$
Equivalent Uniform Annual Cost
$$A = P \left[\frac{i(1 + i)^n}{(1 + i)^n - 1}\right]$$
Present and Future Value
$$F = P(1 + i)^n$$
Light Wavelength and Frequency Relationship
$$c = \lambda f$$
Photon Energy
$$E = hf$$
Feynmann's Trick For Exponential Integrals
$$\int_0^{\infty} x^n e^{-tx} dx = \frac{n!}{t^{n+1}}$$
Finite and Infinite Geometric Sums
$$S_n = \frac{a(1-r^n)}{1-r}$$
Convolution
$$(f*g)(t)=\int_{-\infty}^{\infty} f(\tau)g(t-\tau)d\tau$$
Shockley Diode Model
$$I = I_S \cdot (e^{\frac{V_D}{nV_T}} - 1)$$
Schrodinger's Equation
$$\scriptsize i\hbar\frac{\partial}{\partial t}\Psi(x,t) = \left[-\frac{\hbar^2}{2m}\frac{\partial^2}{\partial x^2} + V(x,t)\right]\Psi(x,t)$$
L'Hopital's Rule
$$\lim_{x \to c} \frac{f(x)}{g(x)} = \lim_{x \to c} \frac{f'(x)}{g'(x)}$$
Lorentz Transformations
$$x' = \frac{x-vt}{\sqrt{1-v^2/c^2}}$$