A programming challenge all up in your face.

[H_TeXMeX_H]

<-- Wonders what possible use / real world application this rather complicated programming challange has ... I dunno, maybe it doesn't have a purpose other than to be challanging. Hmmm ... maybe I can come up with one that is a little more appilcable.

[Orethrius]

Aside from the arc-length bit, it seems to be a rather straightforward CAD application of some sort.

[worker201]

What are the other six unknowns?

whoa, step back a second.  I guess the only thing to solve for is x.  x in terms of 7 variables.  Probably need to solve it twice, to account for the +/- thing.

My shitty math skills produced:
x = (b + p - q -r)/(1-m);
and
x = (-b -p + q + r)/(1-m);
but that probably isn't right
I suppose that if this equation has a rational answer, then the line does in fact intersect the circle, isn't that what we're getting at here?


As far as the point, one possible use for something like this is as a control mechanism for vector graphics.  You might have a matrix that defines a line and a matrix that defines a circle, and want to know where, if at all, they intersect.

[pofnlice]

uh oh...2 matrices?

[piratePenguin]

Aside from the arc-length bit, it seems to be a rather straightforward CAD application of some sort.

CAD programs can/should be able to tell you the length of arcs, lines etc.

So you could modify/build a simple CAD program to do this. I was thinking of doing it with SVG and Javascript, but, nah..

[TheQuirk]

<-- Wonders what possible use / real world application this rather complicated programming challange has ... I dunno, maybe it doesn't have a purpose other than to be challanging. Hmmm ... maybe I can come up with one that is a little more appilcable.

The point of computer science isn't writing applicable programs. If you open a CS book, you'll find that a lot of what's discussed has very little, if any, application to the real world.

http://en.wikipedia.org/wiki/Complexity_classes_P_and_NP

A lot of math has no application. Should we stop studying math?

Something I should mention: Before we solve the general question, which has n circles, let's solve a specific case, in which the line intersects one circle, and doesn't intersect a second circle.

Anyway, that solution for x doesn't seem right. I haven't looked at what all the variables mean, but generally, if you're solving a quadratic, you should be using the quadratic formula (which involes a square and a square root). I wrote down part of the solution on a sheet of paper, but as it turns out, the scanner I was going to use isn't working, so I'll have to scan it some time later today (or type it all up in LaTeX).

[worker201]

The point of computer science isn't writing applicable programs. If you open a CS book, you'll find that a lot of what's discussed has very little, if any, application to the real world.

Programming books, however, are all about the applications.  And those are far more common than CS books.  In fact, I don't think the local Barnes&Noble actually has any true CS books.

[H_TeXMeX_H]

Well, I agree with all that. Except math does have a lot of applications, and the parts that are not applicable are probably incorrect. As for this particular challange, I brought up this issue because I found it to be way too specific (any other arrangement of the objects in the figure would result in a useless program) and I mean I just think that it's just too damn challanging and too little motivation

[worker201]

But, if Quirk and I manage to get through it, we'll be better programmers.
(actually, he has probably already written it, so it's just me getting better)

[TheQuirk]

Well, I agree with all that. Except math does have a lot of applications, and the parts that are not applicable are probably incorrect. As for this particular challange, I brought up this issue because I found it to be way too specific (any other arrangement of the objects in the figure would result in a useless program) and I mean I just think that it's just too damn challanging and too little motivation

I think you misunderstood the challenge. You are given a random number of circles with random coordinates. The progam's task is to read and parse the data, and then calculate the length of the path.

Anyway, back to the challenge. I wasn't able to get to a scanner today, so I'll just type everything up real quick in LaTeX. Stay tuned.

[TheQuirk]

There. I'll add more stuff to it as we progress. This is actually a dvi file, not a pdf, so change the extension once you download it (the pdf was too large to upload).

[verwijderd door de beheerder]

[H_TeXMeX_H]

Whoah ... so it's like making a mini CAD program ?!? Damn ... well I give up

[piratePenguin]

Whoah ... so it's like making a mini CAD program ?!? Damn ... well I give up

To an extent. But building a mini CAD program would make this challenge pretty simple, and building a mini CAD program would have plenty of uses.

[worker201]

Uh, how do I download this file?  Clicking the link causes the browser to handle it as a PDF (which it cannot do).  Trying to save the link target fails as well, because it tries to save attachment.php.  I'm using Firefox, and have had the same problem in Linux and Windows.

[H_TeXMeX_H]

I can save it, I just don't know what program can view it ...