The description in textbooks is that sd2 is "more efficient" (fewer operations) than sd. Said textbooks were written in the days when desk calculators were used to compute the things.
The word "obvious" can be removed "can obviously be put on one line" by way of sd2 f. . ----- Original Message ----- From: John Randall <[email protected]> Date: Friday, March 13, 2009 13:31 Subject: Re: [Jgeneral] J with APL To: General forum <[email protected]> > Fraser Jackson wrote: > > John's comment about numerical stability is the wrong way > around. sd is > > clearly more stable than sd2. > > > > a =: i:5 > > b =: 100000000000000+i:5 > > sd a > > 3.31662 > > sd b > > 3.31662 > > > > sd2 a > > 3.31662 > > sd2 b > > 0j1.13112e6 > > Fraser: > > I can't reproduce your result here (your example works > correctly), but I > am not so sure about my claim anyway, so I'll withdraw it. > > I hope these 1-liners are what Don wants. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
