RE: Strange result with exponents...

["jt" <jt@xxxxxx>]

| -----Original Message-----
| [mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Buck

| > | Anyone who uses floating point should know that it is an approximation
| > | and is only accurate to nearly 16 digits. I understand 16 digits of
| > | precision exceeds the experimental accuracy of all known constants of
| > | nature but that doesn't help in the business world.
| >
| > Am I understanding correctly that the 400 doesn't even Need
| floating point
| > to solve all known Scientific math problems??  (Of course, Not
| suggesting
| > it's unnecessary, because of "requirements" of backwards compatibility.)

<snip what was my understanding, also>

| The reference to "...exceeds the experimental accuracy..." means basically
| that there is no known sensor which can measure that precisely.  No
| thermometer can measure temperature differences of
| .0000000000000001 degree;
| no micrometer can measure that small a distance, etc.

The research on sub-atomic particles doesn't require these kinds-a metrics,
either??

| 16 digits provide a
| ridiculously large degree of precision, so we can't really critisise the
| IEEE on that score.

Well, on that point I disagree.  Recalling that the 1st S/38 allowed for a
Unbelieably Whopping 16M *DTAARA, when no machines even HAD that much memory
(except maybe S/365/370, I dunno.) and not many had that much disk (in raw
numbers of computers, not kinds of computers).

| There may be grounds for critisising software that
| insists on _displaying_ those un-precise digits though...

;-)  I always get a chuckle out of accounting and other reports, that show
such things as Total Sales of $203,504,476.23!  The "bean-counters" I know
sure don't think in those terms, even!

| If you'd like to play with floating point fields, here's some quickie SQL
| that will let you see how things look:
|
| CREATE TABLE BUCK/FLOAT (CHARS CHAR (10) NOT NULL WITH DEFAULT,
| FLOAT4 REAL NOT NULL WITH DEFAULT, FLOAT8 DOUBLE NOT NULL WITH
| DEFAULT)
|
| insert into float values ('low',1.23456789E-38,1.23456789012345e-307)
|
| insert into float values ('hi',1.23456789E38,1.23456789012345e308)
| select * from float
| ....+....1....+....2....+....3....+....4....+....5..
| CHARS                FLOAT4                   FLOAT8
| low          1.2345679E-038   1.234567890123450E-307
| hi           1.2345679E+038   1.234567890123450E+308

Perhaps sooner than I think...;-D

| It has been an interesting discussion.  I say we take up
| logarithms like the
| deciBel next.  :-)  (Just kidding)

(snort)  (And that IS interesting, Tom, on a follow-up post)-;