Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,535

A bit primitive, but what do you think? Works?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,481

Hi MathsisFun;

Cool! Can you get it to output in latex if I want it that way? Also how about in addition to the sliders you have size input boxes too.

Here is a problem,

for this one I am getting.

The det(A) is 0 not 3.199999999

Also because the determinant is 0 this matrix is singular, no inverse.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

Offline

**mathsyperson****Moderator**- Registered: 2005-06-22
- Posts: 4,900

Nice page!

Two things:

- When you click on the cell of a matrix, I think it'd be good if the current contents got highlighted so you can type over them.

- When a result has a big negative number (big in size, so -0.00001 would count) then trying to transcribe the result over to a matrix makes that cell only display "-". The value is stored properly though, so it's just a visual thing.

Why did the vector cross the road?

It wanted to be normal.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,481

Hi MathsisFun;

I notice you can directly edit the answer matrix but you cannot store it back into A or B.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

Offline

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,535

Thanks for the feedback! It may take me a while to work on it. First up: the det(A) bug.

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

Offline

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,535

OK, got most of your requests done I think:

* determinant now right for "1 2 3 ..." matrix

* there is now a "latex" option for output. Should work inside a math tag

* use Tab key: it selects entire next cell

* input cells text is now on one line (so "-" should stay attached to text)

* output is now not editable (no time at the moment to handle "parsing" text input ... maybe in future)

(use refresh and look for v0.52 at bottom)

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,481

Hi MathsisFun;

I am happy. Worked fine. Tried it out on inverting the 5 x 5 Hilbert matrix, this has a condition number of around 500 000 to 1 000 000 ( ratio between the largest and smallest eigenvalue). Numerical stability of your method to invert wasn't bad. Incidentally it got the determinant of the the 5 x 5 Hilbert matrix correct.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

Offline

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,535

That's a mean matrix.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,481

Funny thing is I have never seen them used in any application other than for proving how hard they are to invert.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

Offline

**simron****Real Member**- Registered: 2006-10-07
- Posts: 237

The only complaint I can think of probably doesn't apply to many people here, but if both matrices are 10x10, then B gets cut off.

Linux FTW

Offline