Aw: Re: Re: deco-Math project, step 00_a: exact bin and dec 'ranges' (in gnumeric). follow up.

[newbie nullzwei <newbie-02 gmx de>]

thank you,

you are right,

but then frexp() calculates something different to 'extracting the parts (sign, mantissa and exponent) of the IEEE double representation',
(IEEE double mantissa for normalized values has to be [1 .. 2[),  may be frep() calculates exactly half the mantissa and exponent '+1'?

then might be i can use it for 'my' purpose, by doubling the mantissa and subtracting 1 from the exponent, have to investigate,

but yet every call to it produced compiler errors, have seen it somewhere else in the code working, will try to copy, needs some time,

best regards,



b.

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Gesendet: Freitag, 09. Juli 2021 um 01:48 Uhr
Von: "John Denker via gnumeric-list" <gnumeric-list gnome org>
An: "Gnumeric Forum" <gnumeric-list gnome org>
Betreff: Re: Aw: Re: deco-Math project, step 00_a: exact bin and dec 'ranges' (in gnumeric). follow up.

On 7/8/21 4:34 PM, newbie nullzwei wrote:

> works, did similar for testing which algorithm could work, your sheet is a
> little off as 2^53 is not represented as 0,5*2^54 but 1,0*2^53, the mantissa has
> to be normalized to [1 .. 2[ thus 0,5 is wrong, and once you do further
> calculations with erroneous log / int results in col. B, C you run into wrong
> exponent, wrong mantissa, both together seemingly correct result, but wrong in
> the details ... but it is on the right track ...

I have no idea what you're talking about.
Here's a quote from the frexp() manpage:

...