玩一下 Sqrt 開方

Zeuxis  2013-11-08  Notes

Java 的

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class Test {
	public float sqrt(float num) {
		float guess = num / 3;
		float lastGuess;
		
		do {
			lastGuess = guess;
			guess = (num / guess + guess) / 2;
		}while(Math.abs(lastGuess - guess) > 5e-15);
		
		return guess;
	}
	
	public static void main(String args[]) {
		float num = new Test().sqrt(10);
		
		System.out.println(num);
	}
}

Ruby 的

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def sqrt(num)
	guess = num / 3
	
	begin 
		lastGuess = guess		
		guess = (num / guess + guess) / 2
	end while ((lastGuess - guess).abs > 5e-15)

	guess
end

p sqrt(10)

Python 的

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from __future__ import division
import math

def sqrt(num):
	guess = num / 3
	
	while True:
		lastGuess = guess
		guess = (num / guess + guess) / 2
		
		if math.fabs(lastGuess - guess) <= 5e-15: break

	return guess

if __name__ == "__main__":
	print sqrt(10)

參考

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