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| From | Richard Heathfield <rjh@cpax.org.uk> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops |
| Date | 2016-12-09 17:38 +0000 |
| Organization | Fix this later |
| Message-ID | <o2eq4g$kmb$1@dont-email.me> (permalink) |
| References | <f59dc04a-dbf6-4012-a97b-13d3ef9909a0@googlegroups.com> <a6691add-3701-4a38-b760-d7a05f7317bb@googlegroups.com> <ln60mtyq1c.fsf@kst-u.example.com> |
On 09/12/16 17:23, Keith Thompson wrote:
<snip>
> However, storing money values in integers representing the smallest
> unit (cents, mils, whatever), though it's almost certainly better
> than floating-point, doesn't entirely solve the problem. There are
> financial calculations that yield results that are not whole numbers
> of cents or mils. For example, you might need to start with some
> amount of money and then apply one day's interest at 5% per annum,
> compounded daily. Multiplying a whole number by 1.05**(1/365)
> (or is it 360?) will not yield a whole number.
This is why banks typically calculate interest daily but add it yearly
(or twice-yearly or quarterly).
They will have something like this:
foo
{
long int balance; /* or long long int in C99+ */
double interest;
}
and each day they'll do this:
myfoo.interest += (myfoo.balance + myfoo.interest) *
(1.0 + getdayrate());
(Jacob will have a fit if I don't point out that I'm simplifying, and
that precautions are taken against overflow.)
and then at year end they'll do this:
myfoo.balance += myfoo.interest;
myfoo.interest = 0.0;
> There are, as I understand it, consistent rules, set by law, for
> how these calculations are to be performed. Doing the computation
> in a manner that yields a different result than the one required
> by the rules can get you in big trouble.
Yes, that's correct. Well, probably quite small trouble if you didn't do
it on purpose and if the difference is minor. But still trouble, yes.
> I have no idea what those rules actually are, but if I were working
> on financial software I presumably would have to. (It's not
> inconceivable that the rules are written in terms of floating-point
> calculations.)
In the world of insurance (or at least the UK part of it), for example,
roll-up calculations have to be correct to six decimal places at the end
of the roll-up. (So an endowment policy, say, must be correct to within
one ten thousandth of a penny at the end of even a 35-year investment.)
--
Richard Heathfield
Email: rjh at cpax dot org dot uk
"Usenet is a strange place" - dmr 29 July 1999
Sig line 4 vacant - apply within
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Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Potomac <ravine557@gmail.com> - 2016-12-05 06:32 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-05 08:34 -0700
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-05 15:43 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-05 10:41 -0700
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-05 15:37 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops John Bode <jfbode1029@gmail.com> - 2016-12-05 10:43 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops potomac <ravine557@gmail.com> - 2016-12-07 01:13 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-07 10:55 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Philip Lantz <prl@canterey.us> - 2016-12-07 20:34 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-08 11:08 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Ian Collins <ian-news@hotmail.com> - 2016-12-08 08:23 +1300
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops potomac <ravine557@gmail.com> - 2016-12-07 01:07 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-07 08:46 -0700
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-07 16:23 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops potomac <ravine557@gmail.com> - 2016-12-07 01:12 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-07 08:49 -0700
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops John Bode <jfbode1029@gmail.com> - 2016-12-07 15:07 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops potomac <ravine557@gmail.com> - 2016-12-07 03:46 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-07 11:59 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-07 12:05 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Keith Thompson <kst-u@mib.org> - 2016-12-07 09:40 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-07 15:13 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-07 20:24 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-07 16:28 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-07 21:48 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-07 17:02 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-07 22:19 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-07 17:27 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-07 22:51 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-08 09:10 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-08 14:13 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops David Brown <david.brown@hesbynett.no> - 2016-12-08 15:57 +0100
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Ian Collins <ian-news@hotmail.com> - 2016-12-08 18:02 +1300
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Keith Thompson <kst-u@mib.org> - 2016-12-08 08:48 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops jameskuyper@verizon.net - 2016-12-07 15:33 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-08 09:13 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-08 14:22 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops David Brown <david.brown@hesbynett.no> - 2016-12-08 16:03 +0100
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-08 10:44 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Melzzzzz <Melzzzzz@zzzzz.com> - 2016-12-08 15:48 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-08 21:41 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-08 16:16 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-08 21:47 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops jameskuyper@verizon.net - 2016-12-08 20:16 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops David Brown <david.brown@hesbynett.no> - 2016-12-09 11:19 +0100
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops supercat@casperkitty.com - 2016-12-09 08:00 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-13 13:10 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops jameskuyper@verizon.net - 2016-12-13 13:55 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-15 01:13 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops jameskuyper@verizon.net - 2016-12-15 07:02 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-15 19:56 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops supercat@casperkitty.com - 2016-12-18 10:00 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops supercat@casperkitty.com - 2016-12-14 11:45 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Keith Thompson <kst-u@mib.org> - 2016-12-14 12:14 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-15 01:24 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops supercat@casperkitty.com - 2016-12-15 08:02 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Keith Thompson <kst-u@mib.org> - 2016-12-15 12:10 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Philip Lantz <prl@canterey.us> - 2016-12-16 20:00 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 11:05 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 16:21 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops jameskuyper@verizon.net - 2016-12-09 13:10 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 23:44 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops supercat@casperkitty.com - 2016-12-10 10:18 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-11 16:18 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 08:26 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 11:15 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 16:31 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 23:47 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-11 16:05 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-11 16:21 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-11 23:15 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-11 18:57 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-12 00:05 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-11 21:09 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-12 08:25 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-10 07:59 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops jameskuyper@verizon.net - 2016-12-08 13:51 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops jameskuyper@verizon.net - 2016-12-08 13:34 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-08 21:52 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops jameskuyper@verizon.net - 2016-12-08 19:33 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 11:20 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops jameskuyper@verizon.net - 2016-12-09 13:28 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 23:51 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 16:46 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops "James R. Kuyper" <jameskuyper@verizon.net> - 2016-12-09 13:55 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-07 20:17 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Keith Thompson <kst-u@mib.org> - 2016-12-07 12:23 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops twalker470@googlemail.com - 2016-12-07 05:50 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-07 08:55 -0700
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-07 16:23 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-07 10:56 -0700
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops potomac <ravine557@gmail.com> - 2016-12-07 04:14 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Barry Schwarz <schwarzb@dqel.com> - 2016-12-07 11:03 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops John Bode <jfbode1029@gmail.com> - 2016-12-09 08:06 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Keith Thompson <kst-u@mib.org> - 2016-12-09 09:23 -0800
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 17:38 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops "James R. Kuyper" <jameskuyper@verizon.net> - 2016-12-09 14:01 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 19:09 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-09 12:38 -0700
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-10 00:08 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-10 00:16 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 23:59 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-10 11:51 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-11 16:22 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-11 21:52 +0000
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-11 22:32 -0500
Re: Stumped on the role of a particular statement in a program with Arrays & Nested For Loops Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-12 04:18 +0000
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