Posts

Software Engineering Index

Last edited: August 8, 2025

process of Engineering: chronological order

Other topics

  • Query optimization (TODO)

Fucking acronyms to know

fundamental trade-off of Software Engineering

The MIT vs. New Jersey problem: in Software Engineering, you can only choose one of FAST or ROBUST.

Solving PDEs via Fourier Transform

Last edited: August 8, 2025

This will have no explicit boundary conditions in \(x\)!

Assume \(|U(t,x)|\) decays quickly as \(|x| \to \infty\).

Apply Fourier Transform

Step one is to apply the Fourier Transform on our PDE

\begin{equation} \hat{U}(t, \lambda) = \int_{R} U(t,x) e^{-i\lambda x} \dd{x} \end{equation}

Leveraging the fact that Derivative of Fourier Transform is a multiplication, we can simply our Fourier transform in terms of one expression in \(x\).

Apply a Fourier Transform on \(f(x)\)

This allows you to plug the initial conditions into your transformed expression above.

solving systems

Last edited: August 8, 2025

So let’s say given a system:

\begin{equation} \begin{cases} x + 2y + z = 0 \\ 2x + 0y - z = 1 \\ x - y + 0z = 2 \end{cases} \end{equation}

We can represent this using a matricies.

\begin{equation} \begin{pmatrix} 1 & 2 & 1 \\ 2 & 0 & -1 \\ 1 & -1 & 0 \end{pmatrix} \begin{pmatrix} x \\ y \\ z \end{pmatrix} = \begin{pmatrix} 0 \\ 1 \\ 2 \end{pmatrix} \end{equation}

Songs that need Lyrics

Last edited: August 8, 2025
  • “laws.als”: “drumuomup”
  • “ping.als”: “walking down the street, eating children”""
  • “planets.als”: “sing a song among the starlight”
  • “songs.als”: “thank you klint for your discussion”

Other things I have to finish

  • “Tunel2.als”

sorting functions

Last edited: August 8, 2025

qsort: sort an array of any type

bsearch binary search of an array of any type

lfind: linear search in a array of any find

lsearch: lfind, but perform insertion as well