How do i convert a fixed point number into a float?

Question

Using Unity. I need to used fixed point to network some data deterministically. How do I convert a fixed point back into a float so that I can apply it to the objects transform?

public class Fixed
{
    private int front;
    private int back;

    private const uint MAX_32 = 4294967295;
}

This is the class I have for the fixed point number.

Why do you not use the type "Decimal" as a fixed point number? — NineBerry, Apr 18 '23 at 00:42
[C# fixed point to floating point](https://stackoverflow.com/questions/5728897/c-sharp-fixed-point-to-floating-point) — Retired Ninja, Apr 18 '23 at 00:55
Is it not just `front+(double)back/MAX_32` or `double res = back; res = front + res/MAX_32` to avoid explicit conversions? — Lutz Lehmann, Apr 18 '23 at 09:52

score 0 · Answer 1 · answered Apr 18 '23 at 14:45

Don't overthink it. Just scale your real number by a constant amount (ideally a power of two or ten, depending on your needs) and store in an integer. To convert back, divide by the same amount. In your case, consider multiplying the floating-point value by 4294967296.0 and assigning to a long.

score 0 · Answer 2 · answered Apr 23 '23 at 08:27

0

As @NineBerry said, you can use the type Decimal to represent fixed point numbers:

    decimal fixedPointNum = 123.456m; // a fixed point number
    float floatNum = Convert.ToSingle(fixedPointNum); 
    Console.WriteLine(floatNum);

answered Apr 23 '23 at 08:27

zhuang liu

1

2

You could inform yourself what a fixed-point number is. The aim is to simulate real numbers in a very restricted subset using only a small number of integer operations. This is quite the opposite to a multi-precision floating-point format, regardless of if that is implemented using 2 or 10 (or some power of them) as base. – Lutz Lehmann Apr 23 '23 at 08:38

score 0 · Answer 3 · answered Aug 08 '23 at 07:51

The answer depends on the range. If you are trying to represent the decimal numbers from (-1, +1) you could divide the input by 0x7FFFFFFF.

If you have some other range (let us say -256.0, 255.0) you could divide the input by 0x007FFFFF

It all depends what ranges are you expecting in your inputs

How do i convert a fixed point number into a float?

3 Answers3