I already was... 2008/9/9 Matthieu Brucher <[EMAIL PROTECTED]>
> Use 1./n instead of 1/n. If n is an integer, 1/n equals 0. > > Matthieu > > 2008/9/9 Hanni Ali <[EMAIL PROTECTED]>: > > Hi Matthieu, > > > > Interesting example thanks. I can't however seem to get anything other > than > > zero for the 100,000 to 1 sum. > > > > Cheers, > > > > Hanni > > > > 2008/9/9 Matthieu Brucher <[EMAIL PROTECTED]> > >> > >> > I now have a distinct dislike of float values (it'll probably wear off > >> > over > >> > time), how can the sum of 100,000 numbers be anything other than the > sum > >> > of > >> > those numbers. I know the reasoning, as highlighted by the couple of > >> > other > >> > e-mails we have had, but I feel the default should probably lean > towards > >> > accuracy than speed. 2.0+2.0=4.0 and 2.0+2.0.....=200,000.0 not > >> > 2array.sum() > >> > != 200,000... > >> > >> In that case, we should not use doubles, but long double or even > >> better, the real numbers themselves. Which would mean that > >> computations would be very very very slow. > >> Numpy leans somehow towards accuracy. If you want more accuracy > >> (because even with double, you can hit the limit very fast), use > >> another type. > >> > >> You said : > >> how can the sum of 100,000 numbers be anything other than the sum of > >> > those numbers > >> > >> This will always be a problem. With doubles, try to sum 1/n > >> (1...100000), you'll be surprized. And then do sum 1/n (100000...1) > >> with float values, and here the result should be better than when > >> using doubles. Numerical issues in scientific computing are tricky. > >> There is no single answer, it depends on your problem. > >> > >> Matthieu > >> -- > >> French PhD student > >> Information System Engineer > >> Website: http://matthieu-brucher.developpez.com/ > >> Blogs: http://matt.eifelle.com and http://blog.developpez.com/?blog=92 > >> LinkedIn: http://www.linkedin.com/in/matthieubrucher > >> _______________________________________________ > >> Numpy-discussion mailing list > >> Numpy-discussion@scipy.org > >> http://projects.scipy.org/mailman/listinfo/numpy-discussion > > > > > > _______________________________________________ > > Numpy-discussion mailing list > > Numpy-discussion@scipy.org > > http://projects.scipy.org/mailman/listinfo/numpy-discussion > > > > > > > > -- > French PhD student > Information System Engineer > Website: http://matthieu-brucher.developpez.com/ > Blogs: http://matt.eifelle.com and http://blog.developpez.com/?blog=92 > LinkedIn: http://www.linkedin.com/in/matthieubrucher > _______________________________________________ > Numpy-discussion mailing list > Numpy-discussion@scipy.org > http://projects.scipy.org/mailman/listinfo/numpy-discussion >
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