jakelevi1996

Solving "Tchisla" in Python

Solve problems from the Tchisla app in Python. Code is in the tchisla.py script below. Parameters for the problem being solved can be modified in the if __name__ == "__main__" block at the bottom of tchisla.py.

TODO:

• Avoid creating strings for expressions until the values have been validated
  • This could involve passing the operator and child expressions to Solver._validate instead of the resulting expression, calculting the value using the Operator.operation attribute or Operator.__call__ method in Solver._validate, and then only creating the resulting expression (including creating its string using the Operator.get_string attribute) if the value is valid
• Change target, n and n_count_target to command line arguments
• Add more comments
• Save dictionaries to file so that the

jakelevi1996

Notes on Python

This is a collection of notes on Python, including useful links, useful snippets, Python implementations of algorithms, and notes on built-in and third-party modules.

TODO: migrate existing Python-related Gists into subsections of this Gist

Contents

• Notes on Python
• Contents

jakelevi1996

Notes on C/C++

These are some notes/useful snippets in C and C++. Unless otherwise specifed, it is assumed that the file in question is saved as .temp.c, and compiled and run with the command gcc ./.temp.c -o ./.temp && ./.temp

Contents

• Notes on C/C++
  • Contents
  • Read and print command line arguments
  • Write to a file

jakelevi1996

Notes on Cuda

This Gist contains notes and useful links about programming in Cuda, a language based on C/C++ for general purpose programming on Nvidia GPUs. Much of these notes are based on the book "CUDA by Example" by Jason Sanders and Edward Kandrot. There is also an example Cuda program, notes on Thrust ("the CUDA C++ template library"), and miscellaneous topics.

Contents

• Notes on Cuda
  • Contents
  • General tips about CUDA
• Example Cuda progrm

jakelevi1996

Programs for making good word choices in Wordle

This Gist contains a couple of Python scripts for making good word choices in the word-game Wordle.

The first script is dumb_wordle.py. It suggests what words to guess without taking into account the information returned by Wordle after each guess. According to this script, the 4 best initial guesses are "raise" (or alternatively "arise"), "clout", "nymph", and "badge". The first 2 guesses are good because they hit all 5 vowels, and the top 4 most common letters to appear in 5 letter words. This script uses the text file "words_alpha.txt" which can be downloaded from this GitHub repository, takes up 4.03 MB of disk space, and contains 370,103 words between 1 and 31 letters long (the only word in this list which is 31 letters long is "dichlorodiphenyltrichloroethane")

The second scr

jakelevi1996

Notes on Gitlab CI

This Gist contains notes on Gitlab CI, including useful resources, an example .gitlab-ci.yml file, and how to set up a Gitlab CI runner on Ubuntu (EG if CI jobs require local hardware).

Contents

• Notes on Gitlab CI
  • Contents
  • Useful resources
• Example .gitlab-ci.yml file

jakelevi1996

Notes on gdb (GNU debugger)

Contents

• Notes on gdb (GNU debugger)
  • Contents
  • References
  • Compiling and opening a program in gdb
  • Useful gdb commands
• Examples

jakelevi1996

Finding eigenvalues using simultaneous iteration

This Gist describes simultaneous iteration, an eigenvalue algorithm for a symmetric NxN matrix A, which can be seen as a continuation of my previous Gist on a conceptually straightforward (albeit practically sub-optimal) eigenvalue algorithm for a symmetric NxN matrix. The algorithm presented here is more practically useful than the one presented in the previous Gist, although still not as practically useful as the implicit QR algorithm.

We want to find the eigenvalue decomposition for the symmetric matrix A; that is, we want to find matrices U and D which satisfy A == U * D * U^T , where U is orthogonal (IE U * U^T equals the identity matrix) and D is diagonal.

Using the power method, we can take an initial guess of an eigenvector u, and repeatedly replace u with the matrix-vector product `A *

jakelevi1996

An impractical symmetric eigenvalue algorithm

This Gist presents a conceptually straightforward (albeit practically sub-optimal) eigenvalue algorithm for a symmetric NxN matrix. It is inspired by "Chapter 7: Unsymmetric Eigenvalue Problems" of Matrix Computations, 4th Edition (Golub, Van Loan), and also uses Householder transformations/QR factorisation (see chapter 5 of Matrix Computations, or my earlier Gist), and the power method.

Let's say N = 5, and we want to find the eigenvalue decomposition for the 5x5 matrix A:

A =
[[ 9.776  2.782  2.048  0.418  3.66 ]
 [ 2.782 8.813 1.521 6.218 1.6 ]

jakelevi1996

Making a gif from image files using PIL

The pillow (fork of PIL, the Python Image Library) module presents a simple way to create a gif out of pre-existing image files, demonstrated below. More documentation can be found here. The intermediate image files which are generated by this Gist are not included directly, but can be generated by running the Python script.