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Re: doubt regarding floating point arithmetic Rounding schemes/ Truncation schemes



http://www.math.cmu.edu/~shlomo/VKI-Lectures/lecture1/node5.html
and http://www4.ncsu.edu/~mtchu/Teaching/Lectures/MA529/chapter1.pdf are too mathematical


Robert Myers wrote:

On 19 Nov 2003 22:49:59 GMT, [EMAIL PROTECTED] (Nick Maclaren) wrote:


In article <[EMAIL PROTECTED]>,
vc  <[EMAIL PROTECTED]> wrote:

Rounding schemes/ Truncation schemes

The choice of schemes decides the max error and bias.

Correct.



Zero bias schemes on an average cause little error but there is a large chance htat they might hav a bias too and not end up with an error of zero. Am I right or wrong

I am not quite sure what you mean, but I think that you are roughly right. Most zero bias schemes have no bias, assuming that the errors are uniformly distributed. True probabilistic (stochastic) rounding has no bias, whatever the distribution of errors, but has twice the mean square error and makes debugging slightly (!) harder.


When I saw the subject line, I thought, now that will get a response from Nick.

For extra credit, you might want to study

http://www.cs.ucla.edu/~stott/mca/CSD-970014.ps.gz

and the links to the literature it provides.  In any case, roundoff
bias isn't likely to matter much one way or the other for
poorly-conditioned problems:

http://www4.ncsu.edu/~mtchu/Teaching/Lectures/MA529/chapter1.pdf

http://www.math.cmu.edu/~shlomo/VKI-Lectures/lecture1/node5.html

http://www.math.princeton.edu/~ellenber/Math204Lects/Week12.pdf

but that probably isn't what the homework problem asked about. ;-).

RM





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