Copyright © 2024 Jiri Kriz,


Modelling Disease Spread

SIR model and other models

Sensitivity and Specificity
  • What is the probability that a person has the disease after he was tested positive?
  • What is the probability that a person does not have the disease after she was tested negative?
Linear Optimization

The linear optimization is explained on a practical industrial case. The Simplex Algorithm is presented. The Excel Solver is described.

Earth Coordinates

I describe the Earth-centered (ECEF) cartesian and spherical coordinates as well as local ENU coordinates. I also derive transformations between them.

Great Circle on the Earth

I derive the equation of the great circle on the spherical Earth, the formula for the shortest distance and other related formulas.


I derive equations of the torus and present an Octave program to draw it.

Zero-knowledge Proof

I present a simple zero-knowledge proof of map coloring with 3 colors.

Mathematics Stack Exchange

My contributions to Math.Stackexchange.