As an experiment, I compared three versions of "sinh": the one we've been discussing, then a version with the first "if." removed and another with both removed. For about 2000 random arguments, they all return the same value. Not conclusive but indicative that the lines have no effect, as one might guess from looking at the code.
On Mon, Apr 29, 2019 at 4:17 PM Raul Miller <[email protected]> wrote: > Um... sure? > > sinh=: DP&$: : (4 : 0) " 0 > if. x>10^.|y do. (1r2*_1^0>y)*x exp |y end. > if. 1<|y do. -:-/x exp y,-y end. > e=. 0.1^x > n=. e (>i.1:) y (^%!@]) 1+2*i.>.0.5*y^.e > +/(x:!.0 y) (^%!@]) 1+2x*i.n > ) > > Your if statements (when triggered) calculate values and then discards > them. > > If, for example, you changed that to: > > sinh=: DP&$: : (4 : 0) " 0 > if. x>10^.|y do. (1r2*_1^0>y)*x exp |y return.end. > if. 1<|y do. -:-/x exp y,-y return.end. > e=. 0.1^x > n=. e (>i.1:) y (^%!@]) 1+2*i.>.0.5*y^.e > +/(x:!.0 y) (^%!@]) 1+2x*i.n > ) > > Then your if statements would be computing values which are the result > of your sinh. > > Or, if you just removed those two lines, your code would produce the > same results it currently produces (with the slight possibility of > eliminating some runtime error cases). > > (I've not attempted to look at your code for numerical accuracy, I am > just commenting on its structure.) > > I hope this makes sense? > > Thanks, > > > -- > Raul > > On Mon, Apr 29, 2019 at 1:33 PM 'Mike Day' via Programming > <[email protected]> wrote: > > > > As may be seen, Roger Hui felt unable to advise re my private enquiry > > on one of his essays > > in the J Wiki. Anyone else feel like commenting on the apparently > > unproductive lines of > > code? > > Thanks, > > Mike > > > > > > -------- Forwarded Message -------- > > Subject: Re: extended precision essay > > Date: Wed, 24 Apr 2019 19:00:47 -0700 > > From: Roger Hui <[email protected]> > > To: Mike Day <[email protected]> > > > > > > > > Hi Mike. Thanks for you msg. I am heavily engaged in other matters now, > > so if you want to have a more timely answer I suggest you query > > [email protected] <mailto:[email protected]>. > > > > > > > > On Tue, Apr 23, 2019 at 6:58 AM Mike Day <[email protected] > > <mailto:[email protected]>> wrote: > > > > Dear Roger, > > > > I've been trying to use material from your Essay on extended > precision > > functions at > > > > > https://code.jsoftware.com/wiki/Essays/Extended_Precision_Functions#Utilities > > > > and am puzzled by apparently unproductive code in the hyperbolic > > functions, > > > > eg > > > > sinh=: DP&$: : (4 : 0) " 0 > > if. x>10^.|y do. (1r2*_1^0>y)*x exp |y end. > > if. 1<|y do. -:-/x exp y,-y end. > > e=. 0.1^x > > n=. e (>i.1:) y (^%!@]) 1+2*i.>.0.5*y^.e > > +/(x:!.0 y) (^%!@]) 1+2x*i.n > > ) > > > > I would expect the if statements either > > > > to modify or produce values for use later in the function > > > > or > > > > to have a "return." before the "end." > > > > Not at all important, but I'd welcome your ideas when you have time. > > > > > > Very sad about John Scholes. I'd guess you enjoyed your > collaboration > > at Dyalog, > > > > Best Wishes > > > > Mike > > > > > > > > --- > > This email has been checked for viruses by Avast antivirus software. > > https://www.avast.com/antivirus > > > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Devon McCormick, CFA Quantitative Consultant ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
