Andrew Nikitin posted the expression to the forum 2009-11-03 http://www.jsoftware.com/pipermail/programming/2009-November/016746.html. You can derive it by more conventional expressions for computing the totient, such as the expression */(p-1)*p^e-1 which immediately precedes it in the dictionary.
On Sun, Apr 2, 2017 at 12:39 AM, Martin Kreuzer <[email protected]> wrote: > Hi all - > > In section 'Primes' of the Vocabul I found this line of code (at the very > end, function no 5): > > (- ~:) &. q: y > > I do know that it is another way to calculate the totient of y, and > I'm somehow familiar with the use of (~:) and (&.) and (q:), but > have not yet found any documentation of this construct (- ~:) > [btw, these seem to work too (+ ~:), (* ~:), (% ~:)] > > Where should I explore further..? > > -M > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
