RE: [PHP] Math Weirdness

> I am totally buffaloed by a set of very simple calculations that I am

> doing;

>

> /* calculate total balance with payments and adjustments */

> $totalBalance = $acct['BALANCE'] + $adjBalance;

> echo number_format($totalBalance, 2, '.', '')."\t";

>

> /* calculate total charges */

> $totalCharges = $intlLDCharges + $longDistance + $smsCharges +

> $daCharges + $totalData + $roaming;

> echo number_format($totalCharges, 2, '.', '')."\t";

>

> /*

> * calculate difference between total balance and total charges

> * if the amount matches the ending balance then all is OK

> * if not calculate the difference

> */

> $totBalDiff = $totalBalance - $totalCharges;

> if($totBalDiff === $endingBal){

> echo "OK\t";

> } else {

> /* what is the difference between the ending balance and the

> charges? */

> $totChargeDiff = $endingBal - $totalCharges;

> echo number_format($totChargeDiff, 2, '.', '')."\t";

> }

>

> Each number represented by a variable in all of these calculations has

> been rounded to 2 decimal points at the point they are generated. For

> the most part this works just hunky-dory but I have a handful of calcs

> (out of 300k plus records) that look like this....

>

> $endingBal 0.10

> $totalBalance 0.30

> $totalCharges 0.20

> $totalChargeDiff -0.10

>

> The balance minus the charges does equal the ending balance as it

> should but it is saying that it doesn't and that there a 20 cent swing

> (-0.10 is 20 cents different than 0.10).

>

> I must be missing something. When I echo out raw data I do not see

> negative signs. Does anyone have any insight as to what might be

> happening here?



I don't quite understand your problem, but I use integers for any monetary
workings as you can guarantee it is accurate (obviously, you work in pence
or cents rather than GBP or USD).



Alex

>
> I don't quite understand your problem, but I use integers for any monetary
> workings as you can guarantee it is accurate (obviously, you work in pence
> or cents rather than GBP or USD).
>
>
>
> Alex
>

Hello Alex,

I was reading through this thread, and I was curious about what methods
you use to handle fractions of a dollar and/or fractions of a penny if
you are always using integers. Do you only use a decimal for printing?
do you adjust all interest rates, etc...then as well? How about when
interest calculations result in fractions of pennies, how do you handle
it then? Basically, I can't see how it could be done with just integers
alone?

thanks

dank

I don't quite understand your problem, but I use integers for any monetary
workings as you can guarantee it is accurate (obviously, you work in pence
or cents rather than GBP or USD).



Alex


Hello Alex,

I was reading through this thread, and I was curious about what methods you
use to handle fractions of a dollar and/or fractions of a penny if you are
always using integers.* Do you only use a decimal for printing?* do you
adjust all interest rates, etc...then as well?* How about when interest
calculations result in fractions of pennies, how do you handle it then?*
Basically, I can't see how it could be done with just integers alone?*

thanks

dank

To be honest, I haven't used it for any complicated use - shopping carts are
additive contraptions. However, I don't see the problem.

1) I use Smarty a lot - I use a plugin to format the integer to a price (ie
divide by 100 and display in 2 decimal places). So yes, I only put the
decimal place there to print.

2) Why do interest rates need to be changed?? Take £123.45 @ 5%. 123.45 *
1.05 = (12345 [pennies] / 100) [pounds] * 1.05 = (12345 * 1.05) / 100
Same calculation in my mind!! (Tell me if I have missed the point!!)

3) If you have a fraction of a penny - round it!! Surely, that's what the
banks do!! It's a penny!!

I think it can be done with integers alone - let me know if you disagree!!

Alex

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17:58

On Mon, 2008-07-14 at 15:00 -0500, Daniel Kolbo wrote:
> >
> > I don't quite understand your problem, but I use integers for any monetary
> > workings as you can guarantee it is accurate (obviously, you work in pence
> > or cents rather than GBP or USD).
> >
> >
> >
> > Alex
> >
>
> Hello Alex,
>
> I was reading through this thread, and I was curious about what methods
> you use to handle fractions of a dollar and/or fractions of a penny if
> you are always using integers. Do you only use a decimal for printing?
> do you adjust all interest rates, etc...then as well? How about when
> interest calculations result in fractions of pennies, how do you handle
> it then? Basically, I can't see how it could be done with just integers
> alone?

Depends on what you're working with. I don't think banks can get away
with using pennies. But a storefront can usually do so since they don't
charge fractions of pennies and don't offer interest :)

Cheers,
Rob.
--
http://www.interjinn.com
Application and Templating Framework for PHP

On Mon, 2008-07-14 at 21:09 +0100, Alex Chamberlain wrote:
>

> I don't quite understand your problem, but I use integers for any monetary
> workings as you can guarantee it is accurate (obviously, you work in pence
> or cents rather than GBP or USD).
>
>
>
> Alex
>
>
> Hello Alex,
>
> I was reading through this thread, and I was curious about what methods you
> use to handle fractions of a dollar and/or fractions of a penny if you are
> always using integers. Do you only use a decimal for printing? do you
> adjust all interest rates, etc...then as well? How about when interest
> calculations result in fractions of pennies, how do you handle it then?
> Basically, I can't see how it could be done with just integers alone?
>
> thanks
>
> dank
>

>
> To be honest, I haven't used it for any complicated use - shopping carts are
> additive contraptions. However, I don't see the problem.
>
> 1) I use Smarty a lot - I use a plugin to format the integer to a price (ie
> divide by 100 and display in 2 decimal places). So yes, I only put the
> decimal place there to print.
>
> 2) Why do interest rates need to be changed?? Take £123.45 @ 5%. 123.45 *
> 1.05 = (12345 [pennies] / 100) [pounds] * 1.05 = (12345 * 1.05) / 100
> Same calculation in my mind!! (Tell me if I have missed the point!!)
>
> 3) If you have a fraction of a penny - round it!! Surely, that's what the
> banks do!! It's a penny!!

Nope, banks can't round like that when calculating your daily
interest :)

Cheers,
Rob.
--
http://www.interjinn.com
Application and Templating Framework for PHP

On Mon, Jul 14, 2008 at 4:15 PM, Robert Cummings <robert@interjinn.com> wrote:
>
> Nope, banks can't round like that when calculating your daily
> interest :)

If it works in their favor, you'd be surprised what they do.
That's why extending TILA to banks in the US is such a big deal to me,
yet gets no attention.

--
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On Mon, 2008-07-14 at 16:25 -0400, Daniel Brown wrote:
> On Mon, Jul 14, 2008 at 4:15 PM, Robert Cummings <robert@interjinn.com> wrote:
> >
> > Nope, banks can't round like that when calculating your daily
> > interest :)
>
> If it works in their favor, you'd be surprised what they do.
> That's why extending TILA to banks in the US is such a big deal to me,
> yet gets no attention.

I'm not completely sure about the U.S. but banks in Canada are
regulated... fortunately :)

Cheers,
Rob.
--
http://www.interjinn.com
Application and Templating Framework for PHP

> On Mon, 2008-07-14 at 16:25 -0400, Daniel Brown wrote:
> > On Mon, Jul 14, 2008 at 4:15 PM, Robert Cummings
> <robert@interjinn.com> wrote:
> > >
> > > Nope, banks can't round like that when calculating your daily
> > > interest :)
> >
> > If it works in their favor, you'd be surprised what they do.
> > That's why extending TILA to banks in the US is such a big deal to
> me,
> > yet gets no attention.
>
> I'm not completely sure about the U.S. but banks in Canada are
> regulated... fortunately :)
>
> Cheers,
> Rob.

Ok, I may have been wrong about the banks thing - don't quote me on it!!
However, there must be some degree of accuracy?? Which can then be reflected
in your integers.

Alex

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17:58

On Mon, Jul 14, 2008 at 4:28 PM, Robert Cummings <robert@interjinn.com> wrote:
>
> I'm not completely sure about the U.S. but banks in Canada are
> regulated... fortunately :)

They are here, too, to a certain extent. The problem is, they can
create their own rules that cost the customer a fortune, and still
somehow complain that they need to have rates cut, raised, or
otherwise modified so that they can make more of a profit.

I have to empathize with them, though. I don't know how I'd
survive if I was someone like former Wachovia CEO Ken Thompson, who
only got a $7 Million bonus in 2004 (in addition to $11.1 Million in
salary, stock, et cetera). And speaking of Wachovia, using them by
example, the audacity isn't even masked:

"Shares of Wachovia dropped as much as 11 percent to their lowest
level since 1991 after the bank said it might lose as much as $2.8
billion in the second quarter. It declined to offer specifics on how
it plans to reduce balance sheet risk or whether it needs more capital
or might again cut the dividend.

"Wachovia said it approached [Robert] Steel for the [position of
CEO], offering him a package that could total $38.1 million in salary,
bonus and other awards in his first year."


I'm no genius (despite what MENSA may say ;-P), but if I was so
horribly worried about how to begin cutting expenses, the first thing
I'd do is STOP RAISING @$#%ING SALARIES. If I even got a cost of
living increase, I'd be happy.... but if I got an exorbitant cost of
living increase in the millions, you wouldn't hear me complain.

And I'm sure many of you remember when Exxon Mobil CEO Lee Raymond
retired in December of 2006. Despite rising gas and oil prices, he
"was compensated more than $686 million from 1993 to 2005, according
to an analysis done for the New York Times by Brian Foley, an
independent compensation consultant. That is $144,573 for each day he
spent leading Exxon's "God pod," as the executive suite at the
company's headquarters in Irving, Texas, is known.

"Despite the company's performance, some shareholders, academics,
corporate governance experts and consumer groups were taken aback when
they learned for the first time this week the details of Raymond's
total compensation package, including the more than $400 million he
received in his final year at the company."


That's as far OT as I'm going, but it's worth noting how
regulation doesn't do shit if it's not enforced.

--
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At 4:15 PM -0400 7/14/08, Robert Cummings wrote:
>
>
>Nope, banks can't round like that when calculating your daily
>interest :)
>
>Cheers,
>Rob.

I do know that when it comes to interest you pay them, they round up.
When it comes to interest they pay you, they round down -- and why
not? A decision has to be made -- you can't pay someone less than a
penny.

Cheers,

tedd

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