RE: Programming by the mathematically challenged

Couldn't resist.

IF against a constant should be theoretically faster than ADD because
you're using less references and machine code.

Of course, practice could day otherwise, as I've never had the need to
such performance tweak on the i. It looks like RPG III, so I did a small
program to test it. Based on the code you posted, a loop of 100,000,000
ADDs ran for 34s, and the same loop of Ifs ran for 23s.

You never know when you'll absolutely need those 11s, what if you are
asked to program IBM i time bombs?

--
Saludos
Antonio Salazar

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Peter Dow
Sent: Friday, March 12, 2010 2:12 PM
To: RPG programming on the AS400 / iSeries
Subject: Programming by the mathematically challenged

Hi Everyone,

It's Friday, so I thought I'd share the fun.

I had to work with this vintage 2003 RPG program with the following
code:

C $AMT1 IFNE 0
C ADD $AMT1 $AMT
C ENDIF
C $AMT2 IFNE 0
C ADD $AMT2 $AMT
C ENDIF

I just wonder what was going through the programmer's mind: performance
improvement? i.e. an IF is so much faster than an ADD?

*Peter Dow* /
Dow Software Services, Inc.
909 793-9050
pdow@xxxxxxxxxxxxxxx <mailto:pdow@xxxxxxxxxxxxxxx> /