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Fireside Chats

Last edited: August 8, 2025

Fireside Chats are a group of broadcasts by Franklin D. Roosevelt (FDR) which allowed him to speak directly to the people.

Fireside Index

Last edited: August 8, 2025

Below you will find a list of the Fireside articles.

ArticleDate
Welcome to the Fireside<2023-10-16 Mon>
Make Models Go Brrr<2023-10-23 Mon>
Todo Lists<2023-10-30 Mon>
“Let’s find time”<2024-12-13 Fri>
Pipes are so bad<2025-07-06 Sun>

First Order ODEs

Last edited: August 8, 2025

First Order ODEs are Differential Equations that only takes one derivative.

Typically, by the nature of how they are modeled, we usually state it in a equation between three things:

\begin{equation} t, y(t), y’(t) \end{equation}

as in—we only take one derivative.

Sometimes the solution may not be analytic, but is well-defined:

\begin{equation} y’ = e^{-x^{2}} \end{equation}

we know that, by the fundamental theorem of calculus, gives us:

\begin{equation} y(x) = \int_{0}^{x} e^{-s{2}} \dd{s} \end{equation}

First-Order Linear Systems of ODEs

Last edited: August 8, 2025

Consider the case where there are two functions interacting with each other:

\begin{equation} y_1(t) \dots y_{2}(t) \end{equation}

So we have more than one dependent function, with functions \(y_1, y_1’, y_2, y_2’\) and so forth. To deal with this, we simply make it into a matrix system:

\begin{equation} y(t) = \mqty(y_1(t) \\ \dots \\ y_{n}(t)) \end{equation}

For instance, should we have:

\begin{equation} \begin{cases} y_1’ = 3y_1 - 2y_2 \\ y_2’ = -y_1 + 5y_2 \end{cases} \end{equation}

fixed-point iteration

Last edited: August 8, 2025

Fixed point iteration is a method for finding a fixed point of a function, which is a value that remains unchanged when the function is applied to it (i.e., f(x) = x). The method works by repeatedly applying the function to an initial guess:

  1. Start with an initial approximation x₀
  2. Compute successive iterations: xₙ₊₁ = f(xₙ)
  3. Continue until convergence (|xₙ₊₁ - xₙ| < ε) or maximum iterations

    The method converges if the function is a contraction mapping in the neighborhood of the fixed point (|f’(x)| < 1).