Henry Rich wrote: > >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of John Randall >> Sent: Monday, March 27, 2006 4:16 PM >> To: Beta forum >> Subject: Re: [Jbeta] x: 4 * !19 >> >> Henry: >> >> a=:!19 >> 3!:0 a >> 8 NB. floating point >> b=:!x:19 >> 3!:0 b >> 64 NB. extended integer >> >> So in principle x: 4*a is rational, not an integer. > > I don't see how this follows. 4*a is a floating-point number > which is exactly equal to 486580401635328000. When I convert > that to exact, I could see that it might become a fraction > equal to 486580401635328000, or it could become the integer > 486580401635328000. > Here it becomes a fraction that has some other value, which > I don't understand. >
I don't see why 4*a is exactly equal to an integer. > x: 5*2^66 > 368934881474191050000 > > That's more like it. > > x: 111*2^66 > 8190354368727041310000 > > x: 1111*2^66 > 327909322654261021210625r4 > > Something to do with the number of nonzero mantissa bits? > >> >> There is a difference between J504 and J601. J601 gives your result >> below, while J504 gives >> x: 4*a >> 486580401635328000 > > Interesting. > >> >> However, in J601 >> 0j0 ": 4*a >> 486580401635328000 >> >> As I have learned from Roger by asking similar questions >> (e.g. why is the >> real part of a complex number complex and not real), one should not be >> conditioning ones code on the internal types. > > Agreed. I was just playing with the system. > > Henry > > >> >> Best wishes, >> >> John >> >> >> >> >> Henry Rich wrote: >> > Piddling around with x: I find: >> > >> > a =. !19 >> > 3!:3 a >> > e1000000 >> > 08000000 >> > 01000000 >> > 00000000 >> > 00906830 >> > b9027b43 >> > 3!:3 a*4 >> > e1000000 >> > 08000000 >> > 01000000 >> > 00000000 >> > 00906830 >> > b9029b43 >> > x: a >> > 121645100408832000 >> > x: a * 4 >> > 33437550590372456995572480375r68719476736 >> > >> > I don't see why this last result is a fraction, since the exponent >> > looks like about 2^60. >> > >> > Henry Rich >> > >> > >> ---------------------------------------------------------------------- >> > For information about J forums see >> http://www.jsoftware.com/forums.htm >> > >> >> >> ---------------------------------------------------------------------- >> For information about J forums see >> http://www.jsoftware.com/forums.htm > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
