Re: Exponential notation [was: Re: How to calculate/process this one?]
Re: Exponential notation [was: Re: How to calculate/process this one?]
- Subject: Re: Exponential notation [was: Re: How to calculate/process this one?]
- From: Doug McNutt <email@hidden>
- Date: Sat, 27 Apr 2002 12:59:06 -0600
At 10:48 -0700 4/27/02, Paul Berkowitz wrote:
>
On 4/27/02 8:15 AM, "Paul Berkowitz" <email@hidden> wrote:
>
Does anyone know the significance of this amazing number?
An excellent tutorial is the "Apple Numerics Manual" published by Addison Wesley but I'll bet it's out of print. ISBN 0-201-17741-2, January 1986
It describes a variety of floating point and integer formats some of which morphed into what are now called IEEE single (32 bits), IEEE double (64 bits), and IEEE extended (80 bits).
The gospel is ANSI/IEEE Standard 754-1985 but IEEE standards have to be purchased and they're not cheap.
Hardware documentation for the 680x0 microprocessor and its companion floating point processor also have a lot of information in them. They were once free from Motorola.
A Google search for "IEEE double" immediately brought up this
<
http://www.psc.edu/general/software/packages/ieee/ieee.html>
and a whole lot more.
The limit on a signed long integer should be - 2^31 to +2^31-1 but it apparently is truncated by a bit or two in AppleScript to 2^29.
Accuracy of an IEEE double is generally taken to be 15 decimal digits which is determined by the 52 bits allowed for the mantissa. The 10^308 limit is set by the 11 bits of exponent allowed in the format. The limit is fuzzy because when the exponent limit is reached the mantissa can have leading zeros which trades precision for a bit more range.
Users of floating point need to remember that numbers are approximate! Things like 0.1 as a decimal number can never be expressed exactly as an IEEE double. (1/16 can be which is one of the reasons I still like imperial units over metric.)
--
--> If you are presented a number as a percentage, and you do not clearly understand the numerator and the denominator involved, you are surely being lied to. <--
_______________________________________________
applescript-users mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/applescript-users
Do not post admin requests to the list. They will be ignored.