While working on a web project (mainly PHP, JavaScript and CSS in this order) that I started few weeks ago I stumbled with re-factoring the source code such that it runs faster while becomes easier to maintain. OK, the code…

## Upload file to Google Drive programmatically

Nowadays I am writing a WordPress plugin that involves accessing and upload file to google drive programmatically. This process implies the following steps: request an authorization code from the Google Authorization Server get the authorization code and then use it…

## When to use a Venn diagram

Venn diagram is not just that simple but ingenious tool that helps you to solve those complicated set problems. Venn diagram is a powerful tool. A Venn diagram or set diagram is a diagram that shows all possible logical relations…

## Solving ordinary differential equations (ODE)

Introduction In Algebra we have what is called algebraic equation that is an mathematical expression described in terms of an unknown variable x. For instance is an algebraic equation of first order(because the highest order of the x term is…

## Bridge probability of card distribution

Summer is here and some days are more rainy than others. What to do? What to do? Take three of your friends (why not one of yours best friends and two 'enemies') and play a bridge game, for example the…

## Combinatorics and probability

I think that one of the most beautiful branches of mathematics is discrete mathematic, and here I would emphasize the combinatorics and probability theory. Background Introduction Counting How many they are? Factorial Permutations Combinations Probability Background While I was…

## Finding the lexicographic order of permutations

Given a finite alphabet (e.g. {A,B,C,...,Z}) how many different words can you create from these letters knowing that each letter can be used only once? This is just a typical problem of combinatorics and the answer it's quite simple: n!…

## System recovering after accidentally removing sysvinit

In Unix-based computer operating systems, init (i.e. initialization) is the first process started during booting of the computer system. It is just a daemon that is starting just after the kernel and which reads the /etc/inittab file in order to…

## Poker probability

Have you ever wondered what are the chances that you get a quads (four of a kind) when playing poker? Well, that depends on how many cards the hand has because there are several poker variants, right? These kind of…