CONFIRMCLOSE_j_ is not written out to the config file, so checking the box in Edit|Configure|Session has no lasting effect.
Henry Rich > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Roger Hui > Sent: Friday, February 01, 2008 5:23 PM > To: Beta forum > Subject: Re: [Jbeta] J32 Windows hbeta available > > > Another reason for my dislike of NaN. > > This was not what I actually said when I saw the source > of the current problem. > > The telephone company received a complaint that > linemen working in the neighborhood were using > foul language. The district supervisor asked the > linemen to explain, and received the following report: > Joe and me were up on the pole when Joe dropped > his wrench on my head. I said to him, "Really, > Joseph, you must handle your tools with more care." > > > > ----- Original Message ----- > From: Roger Hui <[EMAIL PROTECTED]> > Date: Friday, February 1, 2008 13:30 > Subject: Re: [Jbeta] J32 Windows hbeta available > To: Beta forum <[email protected]> > > > The bug exposed by 2#_1e6 is one worth remembering for > > telling your grandchildren. > > > > 2#_1e6 NB. wrong > > _1000000 _475712 > > > > When moving sets of 8 bytes, there is a speed advantage > > in moving them as 64 bit floats, so in doing n#_1e6 it is > > faster to move n%2 sets of 64 bits each set of which is > > 2 repetitions of _1e6 : > > > > 3!:3 ] _1e6 > > e1000000 > > 04000000 > > 01000000 > > 00000000 > > c0bdf0ff > > > > But look what happens (in J602 gbeta or earlier): > > > > 3!:3 ]2#_1e6 > > e1000000 > > 04000000 > > 02000000 > > 01000000 > > 02000000 > > c0bdf0ff > > c0bdf8ff > > > > The c0bdf0ff (_1e6) got changed to c0bdf8ff (_475712). > > > > 3!:3 ]_. > > e1000000 > > 08000000 > > 01000000 > > 00000000 > > 00000000 > > 0000f8ff > > > > It turns out that if you have a 64-bit pattern that looks like NaN, > > on some compilers (or different versions of the same compiler) > > the generated code quietly changes a bit from 0 to 1. Another > > manifestation of the bug is as follows (in J602 gbeta or earlier): > > > > x=: 240 255{a. > > y=: 8$x > > y = 0 1 0 1 0 1 0 1 {x > > 1 1 1 1 1 1 0 1 > > > > We'd actually discovered this interesting "feature" at around > > 2000, > > but a recent compiler upgrade by one of us at Jsoftware exposed > > the problem anew. The situation is that in C, when x and y > > are > > doubles and you execute the C statement > > x=y; > > it is possible for x and y to be not bit-by-bit identical. > > > > Another reason for my dislike of NaN. > ---------------------------------------------------------------------- > For information about J forums see > http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
