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infinite division problem

MrKong (5)
The purpose of this code is to add 1 + 1/2 + 1/4 + 1/8 + 1/16 ..... but the output is always 1 instead of going 1 , 1.5 , 1.75 ...... i know that the math is right so that's not the problem but there something wrong with how the code is doing it. it would be great if you could find a fix for this.

More Info

the math is based off the idea that if you add 1 + 1/2 + 1/4 + 1/8 + 1/16 ..... you will have to do it an infinite amount of times before you reach 2

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// ConsoleApplication3.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <iomanip>
using namespace std;


int main()
{
	double x = 0;
	double y = 1;
	do
	{
		x += y;
		y /= 2;
		cout << std::fixed << std::setprecision(100) << x << endl;
	} while (x < 3);

	return 0;
}
Last edited on
Gamer2015 (810)
that's because you're doing it wrong.
You want x to be the output, right?
and y to count the denominator, right?

if so, your math is broken.

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#include <iostream>
#include <iomanip>
using namespace std;


int main()
{
	double x = 0;
	double y = 1;
	do
	{
		x += y;
		y /= 2;
		cout << std::fixed << std::setprecision(50) << x << endl;
	}while (x < 200);
	
	return 0;
}
MrKong (5)
Wow that was fast, it seems to be working (i can see it in the 1.9's for a few mili seconds) but its reaching 2. that's mathematically impossible, is it rounding up. If so how do i change that.
Gamer2015 (810)
you can't
it's the limit of computers and floating point datatypes.
you can only be accurate up to a limited number of digits.
mutexe (2372)
MrKong (5)
well thanks for the help, kinda sucks that this is so limited but it was just something to keep me busy.
Gamer2015 (810)
yeah, you can't use 8 byte to store that much information, I'm sorry.
Last edited on
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