World: r3wp

No, I check the balance manually occasionally.

It's really basic. What are you trying to do ?

Responding privately.

I don't understand this:

>> x: "9220"
== "9220"
>> r: "777777"
== "777777"
>> x: to-integer x
== 9220
>> r: to-money r
== $777777.00
>> d: r / x
== $84.36
>> d * x
== $777777.00
>> d * 9220
== $777777.00
>> $84.36 * 9220
== $777799.20
>> d
== $84.36
>>

What is happening there?

I had to post that before I go to sleep. I'll probably have to get 
up sometime through the night to see the answer.

BUILD - 'ins and 'only are good words, it's just that plain words, 
mixed with a lot of other plain words, don't catch your eye, so using 
any other word doesn't solve it for me. That's why I used the set-word! 
syntax in my COLLECT function if you recall. I would probably end 
up using "special" words or marker values, e.g. puting special chars 
around the words, like ~ins~ or *only*, or just using special start/end 
markers. Basically, synthesizing a paren alternative or looking for 
words that are "marked up" in a ceratin way. e.g.

    build [1 [|_ 3 + 2 _| |_ now _|]]		; |_ val _|  = ins val

    build [1 ||_ reduce [3 + 2 now] _|| ]		; ||_ val _|| - only val

    build [1 *this* and *that* but not these] 	; marked words, e.g. *-modified, 
    are reduced

Louis - what you are describing is a MOLD issue - MOLD shows you 
only two decimal digits for the MONEY! datatype

(which looks like less than you expect, doesn't it?)

on the other hand, the "full precision" is used for computing, that 
is why you see the difference

I am afraid, that you may be unable to use the current MONEY! datatype 
implementation for accounting purposes, because you probably don't 
know when you need to take care

(I don't think, you would be able to do better with DECIMAL! either 
due to the same issues)

Ladislav wrote: "you probably don't know when you need to take care." 
 You are right, but I am going to have to learn. I have written a 
double-entry fund accounting program which we are using for our non-profit 
organization for several years. I have just modified it to convert 
rupiahs to dollars. But it also has to be able to convert the dollars 
back to rupiahs properly. Are there any documents I might read to 
educate myself?

Here is samle data showing the problem:

>> d: make object! [
[        reconciled-d: "o"
[        reconciled-c: "o"
[        trans-num: "1232"
[        trans-date: 14-Oct-2006
[        check-num: ""
[        vender: ""
[        debit-fund: "GF"
[        debit-acc: "5003"
[        debit-amount: $84.36
[        debit-desc: ""
[        credit-fund: "GF"
[        credit-acc: "1001"
[        credit-amount: $84.36
[        credit-desc: ""
[        date-entered: 14-Oct-2006
[        user: "LAT"
[        rp-per-dollar: "9220"
[    ]
>> d/debit-amount
== $84.36
>> d/debit-amount * 9220
== $777799.20
>>


The result should be $777777.00, so I am getting 22.2 rupiah too 
many.

the problem you are struggling with isn't REBOL-specific

that is why you cannot find the solution in REBOL documentation

Mathematical rules:
1) do not expect, that a result "exists" unless you know it does

in the case you are describing we get:

$84.35 * 9220 ; == $777707.00
$84.36 * 9220 ; == $777799.20

we can conclude, that there is *no amount* expressible in dollars 
and cents that has got the properties you want it to have

The solution is up to you - you need to know what you really want 
and how to get it.

I guess that if you will be able to describe what you really want, 
there will be no problem to get it

If you're dealing with $777,777  - then I suggest a professional 
accounting package is more appropriate.

I disagree, even when using a professional accounting package we 
need to know what we want to get

graham, my guess is that they are rupiahs, not dollars :)

Louis: Ladislav is right, the money shows you just 2 decimals digits 
and rounds as you can see:
>>  777777 / 9220
== 84.3575921908894
>> to-money 777777 / 9220
== $84.36
>> (to-money 777777 / 9220) * 1000
== $84357.59
>> (to-money 777777 / 9220) * 1000000
== $84357592.19

What is suprise for me is, that it's not possible convert money to 
decimal using:    to-decimal $84.36

I think, that money datatype is almost useless

For example why is not working this?
>> $10 * $10
** Script Error: Expected one of: number! - not: money!
** Near: $10.00 * $10.00
Money is not a number?

The specified unit ($) would also have to be multiplied to be consistent 
there. We had this discussion before when talking about the proposed 
Rebol v3 deci! datatype...  Anyway, I agree there are problems, but 
this works:
>> 10 * $10
== $100.00

Oldes - you *can* convert money! to decimal as follows: second  $84.36 
; == 84.36

I wish I could divide the money in my bank account into $10 amounts 
and then just multiply them, but the bank won't let me. I don't know 
why.

Ok, you are right, I know I can do 10 * $10 and it's probably logical, 
but anyway, for me money is a number and this is new form me:
>> second (to-money 777777 / 9220)
== 84.3575921908894

(anyway, I'm not going to use money datatype)

and it should be possible to do $10 * $10 as in the Louis' example 
above, the number 9220 should be money datatype as well as it is 
number of roupies per dollar  (if I understand it well) so he should 
use RP$9220 if he is using money! for dollars

I doubt, someone is using this feature (currency identifier) with 
money datatype:-)

Louis' example did not multiply two money!s.

and I strongly disagree that you should be able to multiply two money!s.

A currency exchange rate (such as Louis' 9220) includes, as part 
of its definition, two distinct currencies (eg. RP and USD).

Anyway, I don't want to argue this, you should know about how to 
handle units. Everyone should know that 10 Metres x 10 Metres does 
not equal 100 Metres.

All this is very interesting. I appreciate all of your comments. 
Anyway I have a workaround to the problem. First of all, however, 
I need to tell you why I wanted to be able to convert dollars back 
to rupiahs. It was just to save space in the database. I enter rupiahs, 
as that is the currency I am using right now, but the software converts 
it to dollars and saves the dollar amount to the database. To find 
out the  rupiah amount later if needed, I was going to do a reverse 
conversion. The other solution is to simply record the rupiah amount 
in the database also, so that is what I'll do.

by the way, you may use the conversions on the side of the database 
during select

Oldes, please explain. I do not understand what you mean.

mysql> create table test (dolars float(2));
Query OK, 0 rows affected (0.22 sec)
mysql> insert into test values(777777);
Query OK, 1 row affected (0.03 sec)
mysql> select dolars,(dolars / 9220) as rupias from test;
+--------+-----------------+
| dolars | rupias          |
+--------+-----------------+
| 777777 | 84.357592190889 |
+--------+-----------------+
1 row in set (0.01 sec)

So I could get the reverse conversion I want if I were using mysql?

Right now I'm simply using a rebol object database. It would be very 
difficult to change this particular script. But if I ever do something 
like this again I may consider using mysql.

If you are using Rebol, you should probably use decimals, not money 
datatype

(to store it in the database)

Oldes, yes. I can see that you are right. Store in decimal. Display 
in money.

>> r: 777777
== 777777
>> x: 9220
== 9220
>> d: r / x
== 84.3575921908894
>> d * x
== 777777.0
>> to-money d
== $84.36
>>

I've converted the script to decimal, and it works great!

Decimal is converted to money for reports.

Watch out though - your problem wasn't a decimal vs. money problem, 
it was a rounding problem. If you are going to store the dollar equvalent 
in a database make sure to store it as a floating-point value rather 
than a fixed-point like SQL's decimal type. Otherwise you are going 
to run into the same problem when you store the data and retrieve 
it again.