RE: Really big numbers

[Bill Brosch <bbrosch@xxxxxxxxxxx>]

David,

I would drop the recursion and do it in a straight loop.  It would most
likely run faster, and it would definitely use up less resources like
stack space.

Recursion does make a lot of things easier, but it does have its own
cost.  And for something like this, both solutions are equally easy.

My $0.02.

Bill Brosch
Swift Technologies

e-mail: bbrosch@swiftorder.com
web site:       http://www.swiftorder.com
phone:  1-847-289-8339
fax:            1-847-289-8939
 

-----Original Message-----
From: David Morris [mailto:dmorris@plumcreek.com]
Sent: Friday, January 05, 2001 2:02 PM
To: RPG400-L@midrange.com
Subject: RE: Really big numbers


Java & Rexx fans,

In testing it appears that both run at a similar speed and with the same
precision.  I know 
how to do I/O in Java so at this point Java gets the nod.  Also Java
does not have a 
problem with recurssion where rexx is limited to 100 levels, which makes
for an uglier 
solution.  Also, I am not sure how to dynamically set the scale in Rexx.

Here is the Java solution:

public static BigDecimal factorial(int n) {
        if (n == 1)
        {
                return new BigDecimal(1);
        }
        else
        {
                BigDecimal bd1 = new BigDecimal(n);
                BigDecimal bd2 = bd1.multiply(factorial(n - 1));
                
                return bd2;
        }
}

The Rexx looks like:

numeric digits 1500
arg x
y = 1

do i = x to 1 by -1
  y = i * y
end

say y
exit

Thanks for your help and suggestions.

David Morris

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