Matrix for dummies

Matrix for dummies

Post by watsacha » Wed, 23 Oct 2002 07:51:03



Hello, I've tried to find some tutorial about matrixes on the web but...
Found only horrible hard to understand pages.

Does anobody knows a good web tutorial for people like me (so, dummies) ?

Thank you

 
 
 

Matrix for dummies

Post by George Ziniewic » Wed, 23 Oct 2002 08:26:54



> Hello, I've tried to find some tutorial about matrixes on the web but...
> Found only horrible hard to understand pages.

> Does anobody knows a good web tutorial for people like me (so, dummies) ?

   http://www.sjbaker.org/steve/omniv/matrices_can_be_your_friends.html

zin

--

  http://www.zintel.com

 
 
 

Matrix for dummies

Post by John Tsiombika » Wed, 23 Oct 2002 09:27:49


I'm currently writing a series of tutorials on beginning 3D Programming for
a demoscene site and I have recently posted the first part which deals with
that, the mathematics part, vectors and matrices mainly. I tried to do it in
a way that can be easily understood with diagrams and even small animations,
I would be glad if it is of any help, you may check it out at

http://www.demoscene.gr/articles/3dcoding_nuclear/3dcoding_nuc_intro....

Any feedback appreciated...

-- Nuclear / the Lab --


Quote:> Hello, I've tried to find some tutorial about matrixes on the web but...
> Found only horrible hard to understand pages.

> Does anobody knows a good web tutorial for people like me (so, dummies) ?

> Thank you

 
 
 

Matrix for dummies

Post by watsacha » Wed, 23 Oct 2002 17:54:04




Quote:> I'm currently writing a series of tutorials on beginning 3D
> Programming for a demoscene site and I have recently posted the first
> part which deals with that, the mathematics part, vectors and matrices
> mainly. I tried to do it in a way that can be easily understood with
> diagrams and even small animations, I would be glad if it is of any
> help, you may check it out at

> http://www.demoscene.gr/articles/3dcoding_nuclear/3dcoding_nuc_intro.ht
> ml

> Any feedback appreciated...

> -- Nuclear / the Lab --

As often my best reply is : thank you ! Because I'm very happy anytime I
see pages like this one that provide KNOWLEDGE to people (like me).

I've printed the page and will study it carrefully because it's exactly
what I need.

So, now the feedback : if your intention is to talk to dummies (I talk
about math dummies, with programming skills) you should show the result of
the operations you describe.
For example, "The Dot Product of 2 vectors". Would be cool to have an
example, in fact a real world example. I feel that often math are hard to
understand due to the lack of "real world example".
You know, "what the hell is this operation usefull for ??"

But, keep on writing (maybe about quaternions ??) ;-)

Thanks again

 
 
 

Matrix for dummies

Post by watsacha » Wed, 23 Oct 2002 18:02:51


May I ask you a question ?

In my newbie's mind, I think that :
- How a vector can be a vector as with only 3 coordinates I only get a
point. As a vector is a "direction" I need 3 others coordinates, no ?

Do we presume that the start of the vector is 0,0,0 (the origin ??).

For example, when you write the len of a vector is "len = sqrt(x*x + y*y +
z*z))"... Should I read len = sqrt(x1*x2 + y1*y2 + z1*z2)) when x1,y1,z1
are the "start" of the the vector and x2,y2,z2 the "end" ???

Ahem... Don't want to abuse but some another help would be greatly
appreciated ;-)

Thanks again

 
 
 

Matrix for dummies

Post by fungu » Wed, 23 Oct 2002 18:27:30



> May I ask you a question ?

> In my newbie's mind, I think that :
> - How a vector can be a vector as with only 3 coordinates I only get a
> point. As a vector is a "direction" I need 3 others coordinates, no ?

A vector is a direction, not a point.

If you want a vector with a definite start position
then you need both a vector and a coordinate, yes.

Quote:> Do we presume that the start of the vector is 0,0,0 (the origin ??).

No, a vector is a direction in space, it has no position.

Quote:> For example, when you write the len of a vector is "len = sqrt(x*x + y*y +
> z*z))"... Should I read len = sqrt(x1*x2 + y1*y2 + z1*z2)) when x1,y1,z1
> are the "start" of the the vector and x2,y2,z2 the "end" ???

No. x,y and z are the components of the vector.
The position is irrelevent. A vector can be anywhere
in space and the length won't change.

--
<\___/>
/ O O \
\_____/  FTB.

 
 
 

Matrix for dummies

Post by Stephan-Frank Henr » Wed, 23 Oct 2002 18:35:50


"fungus" schrieb im Newsbeitrag ...


> > May I ask you a question ?

> > In my newbie's mind, I think that :
> > - How a vector can be a vector as with only 3 coordinates I only get a
> > point. As a vector is a "direction" I need 3 others coordinates, no ?

> A vector is a direction, not a point.

> If you want a vector with a definite start position
> then you need both a vector and a coordinate, yes.

> > Do we presume that the start of the vector is 0,0,0 (the origin ??).

> No, a vector is a direction in space, it has no position.

> > For example, when you write the len of a vector is "len = sqrt(x*x + y*y
+
> > z*z))"... Should I read len = sqrt(x1*x2 + y1*y2 + z1*z2)) when x1,y1,z1
> > are the "start" of the the vector and x2,y2,z2 the "end" ???

> No. x,y and z are the components of the vector.
> The position is irrelevent. A vector can be anywhere
> in space and the length won't change.


position is the x/y/z coordinate a thing has in a 3d area.

vector is a direction a thing is moving.

picture the following:
a highway with many automobiles on it.
although each automobile has a different position
they basicly all move in the same direction.

A1.Pos != A2.Pos
but A1.Dir == A2.Dir (approximatly)
(unless changing lanes)

there is a nice tutorial on www.gamedev.net

HTH!

cu

frank

 
 
 

Matrix for dummies

Post by John Tsiombika » Thu, 24 Oct 2002 05:36:05


Quote:> In my newbie's mind, I think that :
> - How a vector can be a vector as with only 3 coordinates I only get a
> point. As a vector is a "direction" I need 3 others coordinates, no ?

> Do we presume that the start of the vector is 0,0,0 (the origin ??).

With a coordinate triplet (x,y,z) you can define a point in a given
3-dimensional cartesian coordinate system. Every coordinate system has an
origin, and thus with a coordinate triplet we implicitly define a direction
in relation to that origin.

Quote:> For example, when you write the len of a vector is "len = sqrt(x*x + y*y +
> z*z))"... Should I read len = sqrt(x1*x2 + y1*y2 + z1*z2)) when x1,y1,z1
> are the "start" of the the vector and x2,y2,z2 the "end" ???

No, as I think I mentioned in the first part of my tutorial, that equation
is the 3 dimensional counterpart of the pythagora's rule of the right
triangle (not sure if that's the name exactly but anyway). the lenght of the
hypotenuse is the sqare root of the sum of the sqare of the other sides: A =
sqrt(b^2 + c^2) now in 3D you also include z^2 to that sum (take a loog at
my diagram). so in fact since the angle between the x and y axis is
90degrees, we can consider the vector at hand as the hypotense of a right
triangle that has as its other sides its distance from the y axis and from
the x axis (x and y component). Really look at that diagram, it should be
obvious once you think of it.

Quote:> Ahem... Don't want to abuse but some another help would be greatly
> appreciated ;-)

not at all, if you need anything else just ask.

-- Nuclear / the Lab --