# I need this code

Discussion in 'Javascript' started by greenflame, May 25, 2005.

1. ### greenflameGuest

I need code to compute the determinant and inverse of a matrix. for
example the determinant and inverse of:

[1 2 3 0]
[4 5 6 1]
[7 8 9 2]
[0 1 2 3]

greenflame, May 25, 2005

2. ### Randy WebbGuest

greenflame wrote:

> I need code to compute the determinant and inverse of a matrix.

Then write code to do it. Then post your best attempt.

> for example the determinant and inverse of:
>
> [1 2 3 0]
> [4 5 6 1]
> [7 8 9 2]
> [0 1 2 3]

Looks more like your homework. Is it?

--
Randy
comp.lang.javascript FAQ - http://jibbering.com/faq & newsgroup weekly

Randy Webb, May 25, 2005

3. ### greenflameGuest

This is for a project of mine to make a mini mathematica. I will try to
do it but I am not sure if you all will understand the matrix math.

greenflame, May 26, 2005
4. ### RandomGuest

greenflame wrote:
> This is for a project of mine to make a mini mathematica. I will try to
> do it but I am not sure if you all will understand the matrix math.

.... so you asked us to write the code to do the math that you don't
think we'd understand?

Now that I don't understand.

Keep me posted, though. I am curious.

Random, May 26, 2005
5. ### RobGGuest

greenflame wrote:
> This is for a project of mine to make a mini mathematica. I will try to
> do it but I am not sure if you all will understand the matrix math.
>

This link (on the Wolfram site) provides a general method for
finding the determinant of an n_x_n matrix.

<URL:http://mathworld.wolfram.com/Determinant.html>

The "expansion by minors" technique is explained here:

<URL:http://mathworld.wolfram.com/DeterminantExpansionbyMinors.html>

No doubt you can develop a specific solution for a 4x4 matrix and
hard-code that, or you could produce a general solution that finds the
determinant of any size square matrix. Depending on how you wish to
approach this, the solution will be very different.

You will likely get more assistance if you provide an algorithm that
you are trying to implement, that way you will get input from those
whose forte is optimisation of JavaScript regardless of whether they
understand the mathematics involved (and don't presume they don't).

I played with Mathematica some years ago - had I been able to apply all
the mathematical knowledge I have ever learned (or even stumbled
across), I doubt that I would even have scratched the surface of its
considerable capabilities.

--
Rob

RobG, May 26, 2005
6. ### greenflameGuest

Thanks Rob I will check those sites out. And I will keep you posted.

greenflame, May 27, 2005