I prefer that the float to bigfloat conversion would
(i) not depend on the setting of any global variable other than fpprec
(not on ratepsilon, or ....),
(ii) always evaluate to the nearest bigfloat (unless it is a NaN or other
such exception),
(iii) be coded by extracting the various parts of a float and pasting them
into a big float.
Yes, some users might not understand why bfloat(float(8 / 9)) evaluates
to
8.88888888888888839545643349993042647838592529296875b-1
while bfloat(8/9) evaluates to
8.88888888888888888888888888888888888888888888888888b-1
But many things about floating point numbers mystify users; and (ii)
should be clear to any user that
understands something about floating-point numbers. I prefer (iii) over
other schemes, because
it seems that it should be faster than other methods (float --> rational
--> bfloat) and (assuming
IEEE floats) more reliable.
Barton
Richard Fateman <fateman@cs.berkeley.edu>
Sent by: maxima-admin@math.utexas.edu
01/22/2004 10:35 AM
To: maxima@mail.ma.utexas.edu
cc:
Subject: Re: [Maxima] float to bfloat
The first of these requires a lot less explanation to most people.
In either case a careful explanation should be available so the
behavior is not viewed as a bug.
RJF
_______________________________________________
Maxima mailing list
Maxima@www.math.utexas.edu
http://www.math.utexas.edu/mailman/listinfo/maxima