Re: C Program confused me
On Sat, Mar 13, 1999 at 01:57:58PM +0800, ivan wrote:
>
> Check out sci.math & the sci.math FAQ (lost the url-sorry) - the faq has
> extensive descriptions of several different algorithms for calculating pi.
I don't know if it's there, but I like the Monte Carlo method the best.
You draw a circle in a square (diameter two, square has edges of length two,
too). Then you throw stones and count the nr of stones in the circle, C, and
the number of stones in the square but not in the circle, S, (stones outside of
the square don't count at all --- ignore them).
Then 4*C/(C+S) is near pi.
Of course, you would need a good random number generator to implement this.
/dev/urandom will be slow, but a good choice. Also, to implement this, I
would use coordinates that go diagonally through the square (then a stone
is inside the square iff |x+y| <= 1, which is hopefully faster then |x|<=1
and |y|<=1, and in the circle, iff x²+y²<=1, which is fast, too)
If you use < or <= shouldn't matter, because a line has no area (the limit
should be the same).
But then, this is not the best method to calculate PI, but it has
interesting philosophical implications if you try to define it this way (or
even if you want to proof that this definition is equal to other).
Sorry, I was carried away :) Maybe we need debian-math.
Marcus
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