> -----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. 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
