Perhaps because it's too obvious? "Everyone" knows that formula (including Gauss when he was a boy.)
Another neat expression for it in J: +/1+i.10 55 sumn1=: 2 ! >: sumn1 10 55 ----- Original Message ----- From: Raul Miller <[email protected]> Date: Thursday, June 4, 2009 5:19 Subject: Re: [Jchat] Guy Steele : The Future is Parallel To: Chat forum <[email protected]> > On Thu, Jun 4, 2009 at 4:28 AM, June Kim <[email protected]> > wrote:> > http://groups.csail.mit.edu/mac/users/gjs/6.945/readings/MITApril2009Steele.pdf > Here's a J expression to sum the first n counting numbers: > > sumn=: -:@* >: > > +/ 1+i.10 > 55 > sumn 10 > 55 > > I am disappointed that Guy Steele's paper did not even have a > footnote mentioning this technique. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
