useless (but not o-t) philosophical question in free time during rendering:

What is a spline ?
Is it an object (becouse of shape)?
Is it a data type (becouse appear in declarations)?
Is it a data structure (becouse store points at entries)?
Is it a programing structure (becouse it is way of declaring function)?
Is it new alone category ?

ABX

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> What is a spline ?
> Is it an object (becouse of shape)?
No, there is no shape!

> Is it a data type (becouse appear in declarations)?
Of course.

> Is it a data structure (becouse store points at entries)?
Not really, because not only the declared entries can be adressed.

> Is it a programing structure (becouse it is way of declaring function)?
No, because it isn't programable by the user.

> Is it new alone category ?
No, it's a data type.

Everything only IMHO!
Felix Wiemann

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Felix Wiemann wrote:
> 
> > What is a spline ?
> > Is it an object (becouse of shape)?
> No, there is no shape!

Well, don't forget splines were originally geometric entities; used to
smoothly interpolate between sets of points. We've extended it to other
uses, but...

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I would say that a spline is a function. You give it some data (the
control points and the time value to be evaluated) and it returns some
coordinates. Exactly what functions do.

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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>   I would say that a spline is a function. You give it some data (the
> control points and the time value to be evaluated) and it returns some
> coordinates. Exactly what functions do.
But the user can't control the calculating process (like it is possible with
a function).

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Felix Wiemann wrote:
> 
> >   I would say that a spline is a function. You give it some data (the
> > control points and the time value to be evaluated) and it returns some
> > coordinates. Exactly what functions do.
> But the user can't control the calculating process (like it is possible with
> a function).

Oh, you mean like the way you can control how functions like sin(),
pow() etc. are calculated (?)

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On Mon, 18 Feb 2002 14:28:14 +0100, "Felix Wiemann" <Fel### [at] gmxnet>
wrote:
> > What is a spline ?
> > Is it an object (becouse of shape)?
> No, there is no shape!

it does the same what parametric object, in given range of parameter results
coordinates

> > Is it a data type (becouse appear in declarations)?
> Of course.

so what is content of this data ?
type of spline ?
values for entries ?
results for parameter? (infinite data type?)

> > Is it a data structure (becouse store points at entries)?
> Not really, because not only the declared entries can be adressed.

in a list when you adress entry outside range of index then you just recive
NULL, it's empty result but result

> > Is it a programing structure (becouse it is way of declaring function)?
> No, because it isn't programable by the user.

you can influence output with specified list of tools: adding entry and
changing type

> Everything only IMHO!

me too

ABX

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In article <82f17usvq6kkpubonvcoq3gbfk9seosh58@4ax.com>,
 W?odzimierz ABX Skiba <abx### [at] babilonorg> wrote:

> useless (but not o-t) philosophical question in free time during rendering:
> 
> What is a spline ?
> Is it an object (becouse of shape)?
> Is it a data type (becouse appear in declarations)?
> Is it a data structure (becouse store points at entries)?
> Is it a programing structure (becouse it is way of declaring function)?
> Is it new alone category ?

A function. You give it an input, you get an output based on that input.
It isn't a shape, it doesn't have a surface, the closest thing is that 
it returns spatially related values. It is a data type in the same way 
that textures and objects are data types, but that's nothing unusual in 
POV...anything that can be declared is a data type. It uses a data 
structure, but it isn't used as one, it isn't intended to store and 
retrieve data like arrays (though I guess you could use it to store 
points if you keep track of the t values).

For the other person: "programmability" is not a requirement for a 
function, only providing a result from a set of parameters. You can't 
reprogram the sin(), cos(), or vlength(), but they are still functions.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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> Oh, you mean like the way you can control how functions like sin(),
> pow() etc. are calculated (?)

Hmmm... I actually meant user defined functions, but you're right...

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> > > Is it an object (becouse of shape)?
> > No, there is no shape!
> it does the same what parametric object, in given range of
> parameter results coordinates
But using the parametric object directly creates a shape, using a spline
doesn't create a shape. (I don't know what I'm talking about, so please
correct me, if I'm wrong.)

> > > Is it a data type (becouse appear in declarations)?
> > Of course.
> so what is content of this data ?
> type of spline ?
> values for entries ?
> results for parameter? (infinite data type?)
Type of spline and values for entries.

> > > Is it a data structure (becouse store points at entries)?
> > Not really, because not only the declared entries can be adressed.
> in a list when you adress entry outside range of index then you just
recive
> NULL, it's empty result but result
A list? Which language?

> > > Is it a programing structure (becouse it is way of declaring
function)?
> > No, because it isn't programable by the user.
> you can influence output with specified list of tools: adding entry and
> changing type
Do you mean user defined functions?
They are completely programable by the user.
Or do you mean predefined functions?
Spline are declared at parsing time, so they can't be predefined.

But perhaps splines are predefined (because of the predefined algorithm) and
user defined (because they are declared at parsing time) functions. A
function is a data type, so I think, the answer could be:
A spline is a data type and a function.

Felix

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