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Thread: 1.356f+1.265f=2.6209998

  1. #1
    Junior Member
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    Mar 2011
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    Post 1.356f+1.265f=2.6209998

    While coding i got some unexpected output. like in the following code when i give this two 1.356 1.265 i got he result as 2.6209998. there r error like this for mane pair of number right now i cant remember.
    class Sumfault
    	public static void main(String str[])
    		float f1,f2;
    		System.out.println("Result is: "+(f1+f2));	
    But can anybody explain why this is happening?

  2. #2
    Super Moderator helloworld922's Avatar
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    Jun 2009
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    Default Re: 1.356f+1.265f=2.6209998

    The reason it does that is because of the way floating point numbers are represented. If you want to really understand why it's that result, you can look at Floating point - Wikipedia, the free encyclopedia. Basically it boils down to floating points not being able to exactly represent 1.356f or 2.621f exactly, and because computers almost always use truncation instead of rounding, you get a number smaller than 2.621f (the actual answer).

    1.356f = 0x3FAD9168 = 1.3559999 (slightly smaller than 1.356)
    1.265f = 0x3FA1EB85 = 1.2650000 (exact)
    2.621f = 0x4027BE76 = 2.6209998 (slightly smaller than 2.621)

  3. The Following 2 Users Say Thank You to helloworld922 For This Useful Post:

    anshu4u (March 14th, 2011), JavaPF (March 14th, 2011)