Binary division

Discussion in 'Math' started by asilvester635, Feb 15, 2017.

  1. asilvester635

    Thread Starter Member

    Jan 26, 2017
    68
    3
    One example is from a textbook. It performs a binary division, though I think they made a mistake in their calculations? Also, another one is a solution that I tried working out, but I also think they made a mistake. The answer that I think is wrong is highlighted in yellow. I worked out the subtraction by getting the 2's complementary. I'm pretty sure I did the 2's complementary right.

    Binary division problem from the textbook
    BD1.jpg

    Another binary division problem and its solution
    BD2.jpg
     
  2. AlbertHall

    Distinguished Member

    Jun 4, 2014
    4,021
    915
    To get the 2's complement, you invert the digits and then add one.
     
  3. asilvester635

    Thread Starter Member

    Jan 26, 2017
    68
    3
    That is exactly what I did If you look at my work.
     
  4. MrChips

    Moderator

    Oct 2, 2009
    14,240
    4,174
    In the first example, your analysis is correct.

    In the second example, 1000 is not divisible by 1001. Hence the quotient is 0.
     
  5. WBahn

    Moderator

    Mar 31, 2012
    20,057
    5,644
    It's easy enough to check if the results are correct or not. Do the math.

    Assuming that both G and D (in the first image) are unsigned integers, then what values to G and D represent?

    If you divide G by D what do you get for the integer quotient and the remainder?

    Having said that, it looks like they are mixing up the notions of doing integer division and fixed-point division.

    In the first image G = 9 and D = 46. 46 / 9 = 5 r 1

    But are you sure that this is binary division and not polynomial division? There is a significant difference. The mere fact that they are using the terms 'G' and 'D' imply that this is polynomial division. That is also consistent with how they are adding the additional 0 bits (is the same as multiplying D by x^3 before dividing by G).
     
  6. asilvester635

    Thread Starter Member

    Jan 26, 2017
    68
    3
    Thank you for pointing that out. It is polynomial division. In that case we use XOR to do the subtraction. Thanks.
     
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