Matrices ?

  • Thread starter drag
  • Start date
  • #1
drag
Science Advisor
1,100
1
Greetings !

Can anyone please explain to me, preferably with as
little math and as much theory as possible , how
matrices work in terms of forms and dimensions and what's
the relevant mechanism ?

I mean, I used to program Star Trek spaceships for a computer
game I once made using matrices. But, nobody ever explained
to me how and why it works, those were just meaningless tables
with sprecific relevant operators to me. I also know the
whole addition/multiplication/other operations stuff(though
I can hardly remember it now), but not how and why it works for geometrical forms in various dimensions and stuff.

Thanks ! :smile:

Live long and prosper.
 

Answers and Replies

  • #3
Guybrush Threepwood
520
1
OK so maybe this is a response for a restricted area of matices use but here goes.
I program in OpenGL and I think the other 3D programming stuff has the same principles. To make a 3D scene you have to use coordinate transformation. These transformations (translation, rotation, scaling) can be written as a linear sistem between the coordinates in the old reference system, and the coordinates in the new reference system. Any linear equation system can be expressed in a matriceal form. So this is one of the reasons you use matrices. Also basic matrix operations are easy to program.
 
  • #4
STAii
333
1
Or, in other words ...
You can do all the world transformation without matrices, it is only that matrices is a convinient way to save points, data, and transformations.
(i learned that while trying to learn Direct3D)
 
  • #5
plus
178
1
One of the most interesting things about matrices are than, due to the method of multiplication A * B is not necessarily the same as B * A.
 
  • #6
Sting
157
2
One of the most interesting things about matrices are than, due to the method of multiplication A * B is not necessarily the same as B * A.

Yep, Matrix multiplication is noncommutative and I know some people who failed exams because of it (even though the teacher had mentioned many times).
 
  • #7
Guybrush Threepwood
520
1
Originally posted by plus
One of the most interesting things about matrices are than, due to the method of multiplication A * B is not necessarily the same as B * A.

true, true...
that's why in OpenGL a rotation, followed by a translation doesn't have the same result as a translation followed by a rotation. To do that you have to make some matrix multiplication and since it's not commutative the results are dependent of the order in which you multiply.
 

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