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Asked: 2026-06-17T13:17:46+00:00

OK, I was given a formula to determine a float value between 0.0 and

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OK, I was given a formula to determine a float value between 0.0 and 1.0 using i and j (coordinates of a value in a 2D array). I simply want to know exactly what this formula does. It makes no sense to me. I have implemented it in its own function where the int values of i and j are passed as parameters. Can someone provide an explanation? I don’t HAVE to understand it, as he gave it to us just to use as is, but I really want to know.

float col = float (((i & 0x08) == 0) ^ ((j & 0x08) == 0));

What exactly is going on here?

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1 Answer

  1. Editorial Team

    The result, if plotted with i,j as the x,y coordinates, will be a checkerboard with squares of 8×8 pixels.

    The i & 0x08 and j & 0x08 are just testing a single bit of each axis. That bit will change state every 8 pixels.

    The == 0 will convert each result to a boolean, which evaluates to either a 0 or 1. It also inverts the result, but I don’t think that’s relevant in the overall formula.

    The ^ exclusive-or operator will return 0 if the two are the same, or 1 if they’re different. That’s how you get the checkerboard – the result alternates each time either i or j crosses a boundary.

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