fpu problem

[crou]

To my mind, the problem is that the fpu works in binary

In the most cases, there are problems of accuracy with float. It occurs when the number can't be represented by a sum of 1/(2^n)

Some float numbers can be exactly represented such as 0.5 (1/2^2) or 0.3125 (1/2^3 + 1/2^5) for instance.

That is not the case with 0.1, and the number will be between two possibles representations
Unfortunately, the fpu have never been able to choose the closer value : they always whoose the upper value. That's why you have a 1 at the end of your 0.1000000000000000000000001

It is shocking because with integer numbers, the problem does not exists, but everybody knows that the computer are bad calculators.

Hope this help

[crou]

oops!

this issue was suppose to be a reply. If anybody knows how i can remove it, tell me!

[Plastelin]

Really, this is not a FPU problem, it just C++ klolage problem.
when you work with float never compare 2 floats like 'a == b' use ABS(a-b)< MIN_FLOAT. Never compare float with Zero compare with MIN_FLOAT like: ABS(a) < MIN_FLOAT
[ccode]
#define MIN_FLOAT 0.000001
[/ccode]