This is a Prime Numbers’ Generator from Integers up to 2,000,000,000, written in Turbo Pascal.
This program generates the prime numbers up to a given arithmetic limit, using 4 (four) different known methods. They are all based in modulo algebra. The methods are:
- This uses the mathematical definition of a prime number to generate them. A prime is only divided by 1 and himself. Disadvantage: The method is very slow.
- In this method, each number N is modulo divided only with the half of the numbers below it (N/2). Thus, the search is becoming faster than the first method.
- In the third method, a number, let N, is modulo divided only with the numbers up to
. As a result of that, the generation process is 10 times faster than the previous methods.
- The fourth method is the best of all. It is based on the 3rd method, only it bypass the
praxis, by modulo dividing each number N with the first, the second and the third prime number and then, if there is a residue, it modulo divides N with j, where j is an integer from 
with step 2. The above trick has the eye-blink effect: the method generates primes (within a reasonable range) before you blink your eyes….:-)
