Mathematics

Complex Analysis

Topics Analytic Functions & Cauchy-Riemann Equations Contour Integration & Residue Theorem Laurent Series & Singularities Conformal Mapping Important Theorems Cauchy’s Integral Theorem Cauchy’s Integral Formula Residue Theorem Rouché’s Theorem Maximum Modulus Principle

Discrete Mathematics

Topics Set Theory & Boolean Algebra Logic & Proof Techniques Combinatorics & Counting Graph Theory Number Theory (Divisibility, Modular Arithmetic) Recurrence Relations Finite Automata & Formal Languages Discrete Probability

Important Theorems De Morgan’s Laws (Logic & Boolean Algebra) Pigeonhole Principle (Combinatorics) Inclusion-Exclusion Principle (Counting) Euler’s Formula for Graphs ( Handshaking Lemma ( Chinese Remainder Theorem (Number Theory) Fermat’s Little Theorem ( RSA Cryptosystem & Modular Inverses Master Theorem (Recurrence Relations)

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Icons

All of the site favicons that I use have been generated by contour plots of the complex logarithm and complex exponential functions.

Experiments

HSV | Viridis | Cividis | Inferno | Jet | Magma | Plasma | Rainbow | Turbo

Real

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Imaginary

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Absolute

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HSV | Viridis | Cividis | Inferno | Jet | Magma | Plasma | Rainbow | Turbo

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Linear Algebra

  1. Linear Algebra

Topics Vector Spaces & Linear Independence Matrix Operations & Determinants Eigenvalues & Eigenvectors Linear Transformations Orthogonality & Inner Products Singular Value Decomposition (SVD) Important Theorems Rank-Nullity Theorem Invertible Matrix Theorem Spectral Theorem (Diagonalization of Symmetric Matrices) Cayley-Hamilton Theorem Gram-Schmidt Process Perron-Frobenius Theorem (Positive Matrices)

Optimisation

Mathematical Background

Definition (Axiom)
A foundational statement accepted without proof. All other results are built ontop.

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Functional Analysis

notes

these are some more informal notes that I have made after having taken the rigorous Analysis course.

  • $c_{00}$ can be thought of as 'finite vectors'. all $\mathbb{R}^n$ tuples can be written as elements of $c_{00}$ with infinitely many zeros after the $n$th term.
  • $c_0$ are all sequences that converge to zero. thus they will include all those in $c_{00}$ and more.
  • $\ell^2$ are the vectors that fade fast enough for their energy 𐃏 to stay finite
  • $\ell^\infty$ are the infinite vectors that never blow up – their entries are bounded.

\[c_{00} \subset c_0 \subset l^\infty \]

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Statistics

This page pairs well with Probability.

Table of Distributions

Distribution mass/density function $$S_X$$ $$\mathbb{E}(X)$$ $$\mathrm{Var}(X)$$ $$\phi_X(s)$$
Bernoulli $$\mathrm{Bern}(\pi)$$ $$P(X=1)=\pi\\P(X=0)=1-\pi$$ $$\{0,1\}$$ $$\pi$$ $$\pi(1-\pi)$$ $$(1-\pi)+\pi e^{s}$$
Binomial $$\mathrm{Bin}(n,\pi)$$ $$p_X(x)=\binom{n}{x}\pi^{x}(1-\pi)^{n-x}$$ $$\{0,1,\dots,n\}$$ $$n\pi$$ $$n\pi(1-\pi)$$ $$(1-\pi+\pi e^{s})^{n}$$
Geometric $$\mathrm{Geo}(\pi)$$ $$p_X(x)=\pi(1-\pi)^{x-1}$$ $$\{1,2,\dots\}$$ $$\pi^{-1}$$ $$(1-\pi)\pi^{-2}$$ $$\frac{\pi}{e^{-s}-1+\pi}$$
Poisson $$\mathcal{P}(\lambda)$$ $$p_X(x)=e^{-\lambda}\lambda^{x}/x!$$ $$\{0,1,\dots\}$$ $$\lambda$$ $$\lambda$$ $$\exp\{\lambda(e^{s}-1)\}$$
Uniform $$U[\alpha,\beta]$$ $$f_X(x)=(\beta-\alpha)^{-1}$$ $$[\alpha,\beta]$$ $$\frac{1}{2}(\alpha+\beta)$$ $$\frac{1}{12}(\beta-\alpha)^2$$ $$\frac{e^{\beta s}-e^{\alpha s}}{s(\beta-\alpha)}$$
Exponential $$\mathrm{Exp}(\lambda)$$ $$f_X(x)=\lambda e^{-\lambda x}$$ $$[0,\infty)$$ $$\lambda^{-1}$$ $$\lambda^{-2}$$ $$\frac{\lambda}{\lambda-s}$$
Gaussian $$\mathcal{N}(\mu,\sigma^{2})$$ $$f_X(x)=\\\frac{1}{\sqrt{2\pi\sigma^{2}}}\exp\left\{-\frac{(x-\mu)^2}{2\sigma^{2}}\right\}$$ $$\mathbb{R}$$ $$\mu$$ $$\sigma^{2}$$ $$e^{\mu s+\frac{1}{2}\sigma^{2}s^{2}}$$
Gamma $$\Gamma(\alpha,\lambda)$$ $$f_X(x)=\\\frac{1}{\Gamma(\alpha)}\lambda^{\alpha}x^{\alpha-1}e^{-\lambda x}$$ $$[0,\infty)$$ $$\alpha\lambda^{-1}$$ $$\alpha\lambda^{-2}$$ $$\left(\frac{\lambda}{\lambda-s}\right)^{\alpha}$$

Statistical Inference

Definition (Random Sample & Model)
Let \(X=(X_1,\ldots,X_n)\) be i.i.d. from a parametric family \(\{F_\theta:\theta\in\Theta\subset\mathbb{R}^p\}\). The parameter \(\theta\) is unknown; inference uses the randomness of \(X\) to learn about \(\theta\).

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Probability

This page pairs well with Statistics.

Elements of Probability Theory

Definition (Random Experiment, Sample Space, Events)
A random experiment has uncertain outcomes. The sample space $S$ is the set of all possible outcomes. An event $E$ is a subset of $S$. The certain event is $S$; the impossible event is $\varnothing$.

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Real Analysis

I am finding Real Analysis to be more difficult than any other mathematics that I have studied before. I can seem to verify the truth of statements because they seem right; but I am having a difficult time producing rigorous and correct proofs.

It seems that High-School children (on the internet) are able to self-study Fomin with success. Bitterly, we remind ourselves:

"Comparison is the thief of Joy"—Theodore Roosevelt (probably)

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