Heat Equation
Last edited: August 8, 2025see also two-dimensional heat equation the following relates to 1d
heat distributes by “diffusing”; this is heat \(u\) diffusing across a plate
\begin{equation} \pdv{u}{t} = \pdv[2]{u}{x} \end{equation}
we have, with Dirichlet Conditions:
\begin{equation} u_{k}(t,x) = \sum b_{k} e^{ - \frac{k^{2} \pi^{2}}{l^{2}} t } \sin \qty( \frac{k \pi x}{l}) \end{equation}
and with Neumann Conditions:
\begin{equation} u_{k}(t,x) = \sum b_{k} e^{ - \frac{k^{2} \pi^{2}}{l^{2}} t } \cos \qty( \frac{k \pi x}{l}) \end{equation}
with infinite boundaries:
Hello Internet
Last edited: August 8, 2025Hello Internet is a podcast hosted by Brady Haran and CGP Grey.
Herber Hoover
Last edited: August 8, 2025Herber Hoover is an American president.
Herber Hoover’s response to the Great Depression
- Hoover’s Programs: too little, too late
- Makes business pledge to maintain wages, tax cuts, Smoot-halwey Tariff, bank financial support
- Builds Golden Gate Bridge and the Hoover Dam
- Rejects the idea of the direct federal relief, which is against FDR’s thoughts
heteroskedasticity
Last edited: August 8, 2025Hidden Markov Model
Last edited: August 8, 2025- draw an initial state \(q_1\) from the initial state distribution \(\pi\)
- For each state \(q_{i}\)…
- Drew observe something \(o_{t}\) according to the action distribution of state \(q_{i}\)
- Use transition probability \(a_{i,j}\) to draw a next state \(q_{j}\)
Isolated recognition: train a family of HMMs, one for each word or something. Then, given new data, perform scoring of the HMM onto the features.
components of HMMs
scoring
Given an observation \(o_1, …, o_{T}\) and a model, we compute $P(O | λ)$—the probability of a sequence given a model \(\lambda\)
