AW: Slightly OT: Rounding Negative Numbers

I think it is correct to round -0.875 to 0.87, since what you do is multiply a by 100 (-87.5).
If you round this, the correct value is -87. Divided by 100 = -0.87. So, Java is fine.

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-----Ursprüngliche Nachricht-----
Von: Khedr, Waleed [mailto:Waleed.Khedr_at_FMR.COM] Gesendet: Mittwoch, 28. August 2002 22:19 An: Multiple recipients of list ORACLE-L Betreff: RE: Slightly OT: Rounding Negative Numbers

The way Java calculates round is (int)Math.floor(a + 0.5f)

So you could enforce your rounding algorithm this way:

import java.*;
public class Round {

         public static void main(String[] args) {
                 double a = 0.875;
                 int i_rounded;
                 if (a >= 0) i_rounded = (int)java.lang.Math.round(a*100);
                     else    i_rounded = (int)java.lang.Math.floor(a*100 -
0.5);
                 double z = i_rounded;
                 z  = z / 100;
                 System.out.println(z);
                 }
         }

Regards,

Waleed

-----Original Message-----
Sent: Wednesday, August 28, 2002 11:59 AM To: Multiple recipients of list ORACLE-L

I'm trying to consolidate some numbers generated by a PL/SQL report vs. a Java based report and these seem to be out due to rounding errors on negative numbers.

In PL/SQL if I for example, round to 2 decimal places:

SQL> select round(-0.875,2) from dual;

ROUND(-0.875,2)

            -.88

In Java:

import java.*;

public class Round {

         public static void main(String[] args) {
                 double a = -0.875;
                 int i = (int)java.lang.Math.round(a*100);
                 double z = i;
                 z  = z / 100;
                 System.out.println(z);
                 }
         }

>java Round

-0.87

which is 0.01 different (1 pence in this case). If I use positive numbers (+0.875) when the answer is 0.88 for both PL/SQL and Java. PL/SQL's answer looks "more"correct to me for the negative value - but what is the mathematically correct rounding of -0.875?!

Thanks!

• Bill.

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