Hi,
My question is purely theoretical.
I add use in my time in University some software that use "extended
type".
For each variable, we define the mandatory "classic type" as integer,
float, double array of.
And we define an optional "extended type" as the unit in the MKSA
system (Meter, Kilogra
On Tue, Jan 25, 2005 at 10:40:15AM +0100, Pailloncy Jean-Gerard wrote:
> Hi,
>
> My question is purely theoretical.
>
> I add use in my time in University some software that use "extended
> type".
> For each variable, we define the mandatory "classic type" as integer,
> float, double array of.
# [EMAIL PROTECTED] / 2005-01-25 10:40:15 +0100:
> I add use in my time in University some software that use "extended
> type".
> For each variable, we define the mandatory "classic type" as integer,
> float, double array of.
> And we define an optional "extended type" as the unit in the MKSA
>
Is CREATE TYPE what you're looking for?
http://www.postgresql.org/docs/8.0/static/sql-createtype.html
No. I'll try to give an exemple of what I want:
I suppose I have the following table
CREATE TABLE experiment (
distanceDOUBLE,
timeDOUBLE,
speed DOUBLE
)
Martijn van Oosterhout wrote:
On Tue, Jan 25, 2005 at 10:40:15AM +0100, Pailloncy Jean-Gerard wrote:
This "extended type" was wonderful, because there was warning/error if
"extend type" does not match in any computation: you can not add apple
to orange.
I think it's a wonderful idea. You could u
On Tue, Jan 25, 2005 at 05:17:21PM +0100, Alban Hertroys wrote:
> Martijn van Oosterhout wrote:
> >I think it's a wonderful idea. You could use a similar mechanism to
> >implement:
> >
> >- Currencies (so you can't add dollars to pounds)
> >- Timezone aware timestamps (so a time in Australia looks
Martijn van Oosterhout writes:
> We're talking here about a database with indexes to speed up
> intersection tests for arbitrary polygons, extensions to handle
> encryption, full text indexing and even builtin XML support.
... none of which require any extensions to the core type system.
AFAICS
On Tue, Jan 25, 2005 at 02:31:40PM -0500, Tom Lane wrote:
> AFAICS this could easily be implemented as a user-defined type, along
> the lines of
>
> CREATE TYPE measurement AS (value double, units text);
>
> and if you want to constrain a particular column to contain only one
> value of uni
Martijn van Oosterhout writes:
> On Tue, Jan 25, 2005 at 02:31:40PM -0500, Tom Lane wrote:
>> AFAICS this could easily be implemented as a user-defined type, along
>> the lines of
>> CREATE TYPE measurement AS (value double, units text);
>> and if you want to constrain a particular column to conta
... none of which require any extensions to the core type system.
AFAICS this could easily be implemented as a user-defined type, along
the lines of
CREATE TYPE measurement AS (value double, units text);
and if you want to constrain a particular column to contain only one
value of units, us
Pailloncy Jean-Gerard <[EMAIL PROTECTED]> writes:
> I do not want for each column and each row to store the value and the
> unit.
> I do want to put the unit in the definition of the column and the check
> on the parser before any execution.
If you do that, you foreclose the ability to store mi
Tom Lane wrote:
Pailloncy Jean-Gerard <[EMAIL PROTECTED]> writes:
I do not want for each column and each row to store the value and the
unit.
I do want to put the unit in the definition of the column and the check
on the parser before any execution.
If you do that, you foreclose the ability to
On Tue, Jan 25, 2005 at 11:41:28PM +0100, Pailloncy Jean-Gerard wrote:
> I have begining to put all the SI unit in a table.
> I am writing the function to check the unit in a standard way.
> I plan to use the user-defined type proposed by Tom Lane.
> The check are done at execution time.
>
> But I
On Wed, Jan 26, 2005 at 09:06:16AM +, Richard Huxton wrote:
> Tom Lane wrote:
> >If you do that, you foreclose the ability to store mixed values in a
> >single column, in return for what? Saving a couple of bytes per value?
> >(I suppose that in a serious implementation we'd store the units as
It strikes me that the right level of constraint is the quantity being
represented: length / mass / time / velocity.
Then you could store any of: '1inch', '2m', '3km', '4light-years' in a
"length" column.
Ofcourse, only one of those is in SI units :) Just like the interval
type, all this could be h
On Jan 26, 2005, at 20:06, Pailloncy Jean-Gerard wrote:
It strikes me that the right level of constraint is the quantity
being
represented: length / mass / time / velocity.
Then you could store any of: '1inch', '2m', '3km', '4light-years' in
a
"length" column.
Ofcourse, only one of those is in S
On Wed, Jan 26, 2005 at 12:06:15PM +0100, Pailloncy Jean-Gerard wrote:
> If I have a column with "speed DOUBLE(m1s-1)"
> I want to be able to put in in any unit format.
> If I want special output, I would have a function
> doubleunit_to_char(speed,'si') that will output "3 m/s" and
> doubleunit_to_
Hi all,
I wonder if it makes sense to implement the units as separate data types
? Cause that's what they are really.
So "amper" would be a data type which aliases one of the numeric data
types (depending on what precision range you need), but does not allow
to be added with anything else than "am
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That's not necessarily a constant; there is evidence to suggest that
the speed of light is slowing down over time. If that is indeed the
case, then as light travels more slowly, a light year will become
shorter.
http://www.ldolphin.org/speedo.html
On Wed, 2005-01-26 at 08:45 -0500, Frank D. Engel, Jr. wrote:
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>
> That's not necessarily a constant; there is evidence to suggest that
> the speed of light is slowing down over time. If that is indeed the
> case, then as light travels more slowl
Martijn van Oosterhout writes:
> Now, how to store the relationships between them to handle
> multiplication and division. Probably go back to base types...
I've thought about this myself quite a bit. I decided that trying to implement
multiplication and division is a bad idea.
What you really
If you allow multiplication and division, you'd need to store not only
one type, but an expression like m.s^-2, etc. You'll end up with something
with Maple. Isn't there some free open source algebraic computation
toolkit with equations and units somewhere ?
---(end
I wonder if it makes sense to implement the units as separate data types
? Cause that's what they are really.
So "amper" would be a data type which aliases one of the numeric data
types (depending on what precision range you need), but does not allow
to be added with anything else than "amper". Any
If you allow multiplication and division, you'd need to store not
only one type, but an expression like m.s^-2, etc. You'll end up with
something with Maple. Isn't there some free open source algebraic
computation toolkit with equations and units somewhere ?
Yes and no.
I am in the (slow) proce
ision range you need), but does not allow
to be added with anything else than "amper". Any other interaction
with
other units (read data types) would be achieved by defining the needed
operators on the respective data types (read units).
You'd have to create a postgres datatype for every variatio
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Yep:
http://www-fourier.ujf-grenoble.fr/~parisse/giac.html
Try things like:
convert(4_acre, _in^2)
(I'm in TI-89 mode, if that makes any difference I don't know).
On Jan 26, 2005, at 6:57 PM, PFC wrote:
Isn't there some free open source algebraic comput
Frank D. Engel, Jr. wrote [01/27/05 9:19 AM]:
On Jan 26, 2005, at 6:57 PM, PFC wrote:
Isn't there some free open source algebraic computation toolkit with
equations and units somewhere ?
A very simple but effective system that I have used quite a lot for
"computation with units" is a Python modul
> Frank D. Engel, Jr. wrote [01/27/05 9:19 AM]:
> > On Jan 26, 2005, at 6:57 PM, PFC wrote:
> >
> >> Isn't there some free open source algebraic computation toolkit with
> >> equations and units somewhere ?
You mean like the traditional units program available on virtually all Unix
machines?
Hi,
Some word from my test work.
I try first to just have a parser that can manage a string of unit.
like 'm s-1 kg2.5 A3.5/7.2'
The parser accept :
- any letters for the unit
- a + or - or nothing before the power
- a fractional power
- the unit separator is space ;-/
The system normalize the frac
De: [EMAIL PROTECTED]
Objet: Rép : [GENERAL] Extended unit
Date: 28 janvier 2005 18:18:18 GMT+01:00
À:[EMAIL PROTECTED]
I have done a new version with
- a new conversion function
- possibility to enter value as fraction
- addition of the operator
Greg Stark wrote:
You mean like the traditional units program available on virtually all Unix
machines?
$ units
2084 units, 71 prefixes, 32 nonlinear units
You have: 1 lightyear/fortnight
You want: m/s
* 7.8213711e+09
/ 1.2785482e-10
That's the program I sugg
On Mon, Jan 31, 2005 at 11:57:41AM +0100, Alban Hertroys wrote:
> Greg Stark wrote:
> >That's the program I suggested writing a function to hand this work off to
> >(presumably in the form of a dynamic library). Keep the postgres code
> >agnostic
> >about the semantics of the units. As long as you
RTFM.
You have: tempK(1)
You want: tempC
-272.15
--
greg
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