you're right the errors remain often too small and invisible to be noticed. also some errors are very rare (for exemple occur only with a certain kind of processor)
but sometimes a very small error can grow exponentially, for exemple when some slightly false value is processed by a slightly false function in an iterative loop or something like that (the false function returns a incorrect value, and then, at the next loop, the false function takes the incorrect value and makes it more incorrect again, on and on ) ... +++++++ clemos On 8/15/06, Marcus Kirsch <[EMAIL PROTECTED]> wrote:
i guess doubles are then the variable equivalent of butterflies then ....... my question as uninitiated would be was the error gone or just so small now that it didnt remain visible marCus > Quoting marc <[EMAIL PROTECTED]>: > >> That's right, one of the most basic operations in math, a thing that >> we learn to do before we can ride a bike, eludes the combined efforts >> of the finest engineers over the last 30 years. Of course, this is >> something that is intuitively nonsensical - why should it be >> impossible to round a floating-point number reliably? > > Real mathematics programmers use bignums. ;-) > > http://en.wikipedia.org/wiki/Bignum > > I remember the first time I saw a floating point rounding error. A > student I was > teaching was rotating a vector shape on the screen by multiplying the > angle by a > fraction in a loop. The numbers were stored as C floats. As the shape > rotated it > started to drift off-centre. I had difficulty believing that floats were > the > problem given the low ranges being used, but after asking the maths > lecturer's > advice we switched the code from using floats to using doubles. The shape > then > rotated without drifting. > > - Rob. > > _______________________________________________ > NetBehaviour mailing list > [email protected] > http://www.netbehaviour.org/mailman/listinfo/netbehaviour > -- Marcus Kirsch MA (RCA) Interaction Designer and Technoartist London, UK +44 (0) 7950 177633 [EMAIL PROTECTED] _______________________________________________ NetBehaviour mailing list [email protected] http://www.netbehaviour.org/mailman/listinfo/netbehaviour
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