Numeric Variables & Computation Statements
Last update: 18 May 2005
Question
What are people's experiences with regards efficiency when comparing the
use of Integer and Packed format variables as counters, indices, or
other such fields?
Answers
From Jim Wisdom and Dieter Storr
- Use I definitions for indices.
- Use packed for any Natural math. I format is better for integer math in general
- Continue to use numeric (N format) for any strictly to-display fields.
An added fact often missed:
If any 'numeric' fields are on Adabas files that are used for arithmetic
reasons, define them as packed for the DDM (easy if you use Predict).
This way, you eliminate data conversion by Adabas when it provides the
data contents on==in the record buffer. I have too often seen where
people define them as D format. Thus means:
- Adabas re-format,
- Natural conversion for math.
- Natural re-convert if these fields are part of WRITE/DISPLAY/PRINT
statements.
This can represent a lot of saved conversion work.
Example
Executed the following program with 16 format combinations.
Each format combination ran 10 times. See the results.
0010 DEFINE DATA LOCAL
0020 1 #SUM (P9) INIT <1>
0030 1 #INCREMENT (P9) INIT <1>
0040 1 #LIMIT (P9) INIT <100000>
0050 * For #SUM and #INCREMENT
0060 * Format combination: P9, N9, I4, F4
0070 END-DEFINE
0080 ST. SETTIME
0090 REPEAT UNTIL #SUM > #LIMIT
0100 ADD #INCREMENT TO #SUM
0110 END-REPEAT
0120 DISPLAY *TIMD(ST.)
0130 END
| ADD |
| #INCREMENT
P9 |
| #INCREMENT
N9 |
| #INCREMENT
I4 |
| #INCREMENT
F4 |
|
| #SUM P9 |
| 2.0 |
| 2.7 |
| 3.6 |
| 7.2 |
|
| #SUM N9 |
| 3.1 |
| 3.2 |
| 3.7 |
| 6.9 |
|
| #SUM I4 |
| 5.7 |
| 12.6 |
| 3.0 |
| 6.0 |
|
| #SUM F4 |
| 5.8 |
| 5.6 |
| 6.6 |
| 4.7 |
|
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