4 hundred quadrillonth?

norseman norseman at hughes.net
Fri May 22 00:45:57 CEST 2009


seanm.py at gmail.com wrote:
> The explaination in my introductory Python book is not very
> satisfying, and I am hoping someone can explain the following to me:
> 
>>>> 4 / 5.0
> 0.80000000000000004
> 
> 4 / 5.0 is 0.8. No more, no less. So what's up with that 4 at the end.
> It bothers me.
======================================

Machine architecture, actual implementation of logic on the chip and 
what the compiler maker did all add up to creating rounding errors. I 
have read where python, if left to its own, will output everything it 
computed. I guess the idea is to show
	1) python's accuracy and
	2) what was left over
so the picky people can have something to gnaw on.

Astrophysics, Astronomers and like kind may have wants of such.
If you work much in finite math you may want to test the combo to see if 
  it will allow the accuracy you need. Or do you need to change machines?

Beyond that - just fix the money at 2, gas pumps at 3 and the 
sine/cosine at 8 and let it ride. :)


Steve



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