"John W. Kennedy" <jwkenne@[EMAIL PROTECTED]
> wrote in message
news:KyjAf.3955$e9.3653@[EMAIL PROTECTED]
> robin wrote:
> > From: "John W. Kennedy" <jwkenne@[EMAIL PROTECTED]
>
> > Sent: Wednesday, January 18, 2006 2:16 PM
> >
> >> robin wrote:
> >>> "John W. Kennedy" <jwkenne@[EMAIL PROTECTED]
> wrote in message
> >>> news:ivXyf.40$gh5.16@[EMAIL PROTECTED]
> >>>> robin wrote:
> >>>>>>>> The 704 family offered double precision, too; it was not fully
> >>>>>>>> implemented in hardware, but the hardware assisted it, and the
FORTRAN
> >>>>>>>> compiler sup****ted it.
> >>>>>>> It had to, in order to meet the standard.
> >>>>>> There was no FORTRAN standard until long afterwards.
> >>>>> IBM set it.
> >>>> So your argument is that the 704 hardware had to implement
> >>>> double-precision floating-point in 1954 in order to sup****t FORTRAN
IV,
> >>>> which didn't even come out until 1962 (two hardware generations
later)?
> >>> You said it ; I didn't.
> >> The bloody quotes are right above.
> >
> > I think that it would be a good idea if you ceased
> > your ridiculous allegations, which have not been based on anything.
>
> You said -- it's quoted right above -- that the FORTRAN compiler for the
> 704 had to sup****t double precision "in order to meet the standard",
> which is absurd, because the FORTRAN compiler for the 704 was the first
> FORTRAN compiler there ever was, and existed long before any standard.
And I replied that IBM set it.
> >>>>>>>>> But for most work, little difference between 36 bits and 32
bits.
> >>>>>>>>> But that's no measure, anyhow. The appropriate measure is
> >>>>>>>>> the number of mantissa bits and range of exponent.
> >>>>>>>> They add up to the word size, one way or the other.
> >>>>>>> Not relevant; what's im****tant is the breakdown --
> >>>>>>> and in particular, the number of mantissa bits.
> >>>>>> In order to make any sense of your argument, I can only assume
that you
> >>>>>> do not know what the words "relevant" and "mantissa" mean. Kindly
look
> >>>>>> them up.
> >>>>> The term "mantissa" has been used since the early days of
computers
> >>>>> to describe part of floating-point number.
> >>>>>
> >>>>> Are you having a bad day?
> >>>> Either you are attempting to argue that the size of the fraction
and the
> >>>> size of the exponent are each more im****tant than one another,
while
> >>>> simultaneously maintaining that word size has nothing to do with
the
> >>>> issue either way, or else you are simply misusing words.
> >>> Are you trying to divert attention from "mantissa"?
> >> We'll try this one more time.
> >>
> >> You argue simultaneously that the "mantissa" is most im****tant and
that
> >> the exponent is most im****tant.
> >
> > If you look again, you will see that I didn't say that.
>
> In one and the same posting, you said, "What's im****tant is ... the
> number of mantissa bits," and then followed it up by indicating that the
> 360 did a good thing by increasing the exponent range at the expense of
> fraction bits. You can't have it both ways.
Again I didn't say that at all. What I did say was that
there were design considerations, in particular the choice of hex
reduced the number of ****fts required for post normalization
from 23 to 5 for single precision, and correspondingly
for double precision (55 and 13). This gave a good range of exponent,
consistent with a reasonable number of mantissa bits.
In\ then invited you to state how you would have done it better ,
and of course there was no response at all.
> >> This means one of two things: you think
> >> "mantissa" means "exponent", or you're contradicting yourself.
> >
> > The only person who doesn't know what "mantissa" means
> > is your self. Do you still think that it is to do with logarithms?
> > And BTW, I didn't contradict myself.
>
> Actually, I didn't raise the issue of logarithms;
YOU raised the question of "mantissa", saying that I didn't
know what the word means, and implying that the word was
used incorrectly, which it wasn't. And isn't.
Whereas in fact, all along it's YOU who doesn't know what
the word means.
> Glen did. However, he
> was right; the use of "mantissa" to mean "fraction component of a
> floating-point number", though widespread, is an abuse, like using "k"
> to mean 1024.
>
> I have already indicated how you contradicted yourself.
No you haven't, because there is no contradiction.
> >>>>>>>> In any case, the
> >>>>>>>> S/360 had significantly fewer effective fraction bits (21) in
single
> >>>>>>>> precision than the 7094 (27).
> >>>>>>> Leaving only 7 bits for the exponent. In other words, a reduced
> >>>>>>> range of exponent, which the S/360 corrected.
> >>>>>> Having trouble with subtraction, are we now?
> >>>>> When I last looked, 27 + 1 + 7 + 1 = 36.
> >>>> Are you under the impression that the 704 series had a 35-bit word
with
> >>>> a parity bit?
> >>> You said 36 bits earlier.
> >> Yes, I did, because it /did/ have 36. But your breakdown above
includes
> >> an extra 1-bit field that cannot be accounted for.
> >
> > I'll leave it for you to work out what the bits might be for.
>
> The actual format of a 704 floating-point number was:
>
> S (it was called S rather than zero): sign
> 1-8: excess-128 exponent
> 9-35: fraction.
Good; you finally worked it out.
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