# Mathedu

Learn math by practice

# Re-engineering Math

## Find Prime Numbers with Scilab®: Programing of the Sieve of Erastothenes

The Sieve of Erasthotenes is a very old algorithm to find by elimination the prime numbers up to a given integer N.

The manual process is so:

1. write down the numbers from 2 to N (say 100)
2. stripe the multiples of 2, except 2
3. stripe the multiples of 3 not yet striped, except 3
4. iterate the process for the next unstriped number k: stripe the multiples of k not yet striped, except k.
5. continue until you get no more unstriped multiples before N

The unstriped remaining numbers are the numbers...

## Infinite in Theory, Finite in Practice

When we start to count on our fingers and continue by heart, we only have a small part of all the possible "natural integers": these are all the possible numbers we may count with.

We know that we may count until very very big numbers, the numbers we may imagine, and even further… These very big numbers may be the size of a Galaxy, the size of the known universe, the number of cells in a human body, in all the human bodies, and so on.

The mathematicians construct the set of all "natural...

## Why real numbers are generally not real

The numbers defined in mathematics are in the increasing complexity order:

- The natural integers, from 0 to infinity, that we use to count

- The relative integers, that are the natural integers plus the negative integers, that we use for instance for accountancy "credit" or "debit" notions

- The rational numbers, that we use to share a quantity: they are the result of divisions

- The real numbers, that are all the possible finite or infinite combination of digits, with or without a...

## A free version of Scilab course

You wish to know more about mathedu's Scilab corse before you buy it?

Get the free version, Scilab for Beginners, you will have the basics of Scilab.

You will know how to use Scilab as a high level calculator, which globally manages matrices, vectors and scalars.

Do not hesitate, it is free of engagement!

## Scilab for Engineers and Scientists: 50% off

Scilab for Engineers and Scientists is THE course to learn the scientific computing software Scilab. And with the MATHEDU coupon, you will have it for half price! Take it NOW!

## Our first course is on line!

Hello, I am Fabienne, the President of Mathedu, and also the creatress of the courses… with the support of my General Manager François.

We are happy to annouce the launch of our first course. For the pilot, we choosed not to teach directly math, but to introduce you to Scilab, the scientific computing software that will help us to pratice math.

The course is titled "Scilab for Engineers ...