Re: Parallel program to calculate PI

Pietro Cerutti said:

> Prime Mover wrote:
>> % descriptive algorithm:
>> 1. Inscribe a circle inside a square
>> 2. Generate random points inside the square
>> 3. Determine the number of points that fell inside the circle
> 
> How can you determine it without knowing PI a priori?

There's nothing in the above description that requires a knowledge of pi.

For example, you can draw a circle of radius r easily enough just by 
applying the equation x^2 + y^2 = r^2 (no, that is not C code!) for all y 
in the range -r to +r, taking the positive result and its negative 
analogue for your x points. (Actually, it's even easier than that, because

there are other symmetries to exploit.)

Determining whether you're in the circle can be done either by tedious 
inspection (a process not unlike floodfill) or (much faster) by 
determining whether x^2 + y^2 <= r^2.

-- 
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www.
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