Improve computations of interval_div to prevent rounding problem on AIX.

src/backend/utils/adt/timestamp.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.144 2005/07/23 14:25:34 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.145 2005/07/23 14:53:21 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2308,9 +2308,9 @@ interval_div(PG_FUNCTION_ARGS)
 	result->day = span->day / factor;
 	result->time = span->time / factor;
 
-	/* Computer remainders */
-	month_remainder = (span->month - result->month * factor) / factor;
-	day_remainder = (span->day - result->day * factor) / factor;
+	/* Compute remainders */
+	month_remainder = span->month / factor - result->month;
+	day_remainder = span->day / factor - result->day;
 
 	/* Cascade fractions to lower units */
 	/* fractional months full days into days */