Re: Float & precision

["David C. Hoos, Sr." <david.c.hoos.sr@ada95.com>]

<fluffy_pop@dsuper.net> wrote in message
news:380b47e6.444543814@news.dsuper.net...
> On Sun, 17 Oct 1999 05:23:55 -0500, "David C. Hoos, Sr."
> <david.c.hoos.sr@ada95.com> wrote:
>
><snip>
> Of course this will not work as simply as that since my intermediate
> result could be of any order of magnitude with positive or negative
> exponent.  So I may have to multiply it by 10^x or divide it by 10^x,
> and then I'd have to figure out what x should be based on the
> intermediate result, so as to bring the value within the interger or
> long integer's range.
>
> Will a typecast into a discrete (integer) value not eliminate those
> non significant digits, thus rounding to a specific position ?
>
No.  Not unless your integer has more bits than the mantissa of the
floating point type, and then, only if a scale factor is chosen such
that there is no overflow.

By the way, "typecast" is not an Ada term.  You probably mean
"type conversion" or "type convert."

> I'm just sort of playing, going beyond the scope of my school work,
> trying to think of a relatively simple way to do it.  After all my
> pocket calculator does it without problems.  It's an old cheap Casio
> model.  I don't know if operates with 32 or 64 bits or maybe something
> else.

The reason your pocket calculator _appears_ to do it without problems,
is that it does the calculations internally with a couple more digits
than it displays.

You can get the same effect in Ada with the gnat compiler by doing
your computations in long_long_float, then converting to long_float
for display.